random musings

Food for thought?

2011-09-08T18:03:00.001+08:00

The other day a friend of mine sent me an article written by a 26 year old who was diagnosed with cancer.

It's a sobering thought and realisation that it could happen to just about anyone regardless of age. People say things like "everyone is going to die of cancer eventually anyway". Such a callous thing to say! It's not that fun when it happens to you

http://www.todayonline.com/Sunday/FaceintheCrowd/EDC110904-0000192/I-have-can...

Thanks!

2011-09-01T23:43:00.001+08:00

ok I'll admit it I *do* love you guys ;)

Out of Office

2011-05-26T09:45:00.001+08:00

Will be out of office until 14 June.

Email or sms if you need to see me then. In the meantime, study hard for your CTs!!!

civics

2011-02-14T16:24:00.001+08:00

Lesson no 1: Punctuality

And a new year begins :)

2011-02-14T16:21:00.001+08:00

Ship Ahoy people!

Untitled

2011-01-17T12:38:00.001+08:00

http://www.q2cfestival.com/play.php?lecture_id=8249&talk=alice

Alice & Bob in Wonderland

2011-01-17T12:31:00.001+08:00

Stuff to think about!

http://www.q2cfestival.com/play.php?lecture_id=8249&talk=alice

See the rest of the videos here.

Power of Ideas - Perimeter Institute

2011-01-17T12:16:00.001+08:00

http://perimeterinstitute.ca/power_of_ideas/index.html

Misconceptions

2011-01-10T21:31:00.001+08:00

http://imgs.xkcd.com/comics/misconceptions.png

Definitely a sign of age..

2010-12-23T14:21:00.001+08:00

see more Lolcats and funny pictures

I can't believe how much I'm amused by this!

What is a Vector?

2010-12-23T13:06:00.001+08:00

"It's a mathematical term, quantity represented by an arrow with both direction AND magnitude...VECTOR.."

Using Newton's Laws to explain the direction of the net force in Circular Motion

2010-10-11T14:58:00.000+08:00

Newton's 1st Law of Motion
A body will continue in its state of rest or uniform motion unless there is an external resultant force acting on it.

Since the body actually turns/rotates/moves in a circle, there is a resultant force acting on it.

Newton's 2nd Law of Motion
The rate of change of momentum of a body is proportional to the resultant force acting on it.

It travels a uniform speed but it's direction is constantly changing. i.e. there is a change in velocity over time and hence a rate of change of momentum, which according to Newton's 2nd Law, implies that a resultant force exists.

Since only a change in direction results from this resultant force, the direction of the force would have to be perpendicular to the direction of motion.

Hence there is a resultant force acting on the object, directed towards the centre of the circular motion.

How to attempt a Projectile Motion Question

2010-04-29T11:24:00.002+08:00

Projectile motion is always tricky with students. I've been there I know, but really it's just a matter of dissecting up the motion of the "flying" object into straight across and up/down.

So let's say we're trying to help Peter on this one,

(I know I use this picture all the time but it just cracks me up!)

If we're looking down from above, we would observe the cannon ball to be moving in a straight line (horizontal motion).

We will also see that (neglecting air resistance) the cannonball moves in a straight line with constant velocity.
Hence by substituting your kinematics equations to this motion, we have the following:

a_x = 0

u_x = v_x

s_x = u_xt

But if we're looking straight at the cannon (at a far enough distance of course) we would observe the cannon ball to go up and then come back down again (vertical motion). So this means that there is acceleration (since speed decreases to zero and the cannon ball actually makes a U-turn back down) and this acceleration is the acceleration of free fall g or 9.81 ms^-2.

Again, by substituting your kinematics equations to this motion, we have the following:

a_y = 9.81 ms^-2

v_y = u_y+ a_yt

v²_y = u²_y+ 2a_ys_y

s_y = u_yt + 1/2 a_yt²

*** make sure that you define a direction and assign the correct signs to the different vectors!

So now we have 2 different sets of equations (horizontal & vertical) describing what is essentially the same motion (the same cannon ball moving in the same path).

This means that if we combine the two sets, we will thus be able to describe what is happening to the cannon ball at any time t.

Eg, the initial velocity of the cannonball u as it leaves the cannon can be described as follows,
magnitude: u² = u²_x + u²_y
at angle to the horizontal of: tan^-1(u_y/u_x)

Same for the velocity at any given time t.

*** remember that the time taken t is the same for both motion descriptions because they are describing the same motion path!

In summary, stuff you need to think about when given a question:

Identify all the data given as u_x , u_y , v_x , v_y , s_x , s_y
Take note whether it is released at an angle (means u_x , u_y>0) or horizontally (u_y = 0)
Is your initial velocity pointing up or down? (if up is +ve then g will be -ve)
Is your final displacement below or above your starting point? (if up is +ve then s below starting point will be -ve)

Let me know if this helped!

eat my red stapler!

2010-04-21T20:03:00.002+08:00

Everyday's an interview kids. We ask, you answer, we observe and when it's recommendation time, we recommend. This is my personal favourite (hint hint)

http://theoatmeal.com/comics/interviewees

So ... which one are you?

Confirmed CT2 (J1) Topics

2010-04-15T10:20:00.001+08:00

The J1 Topics for CT2 are confirmed as follows:

Kinematics
Dynamics (Collisions & Projectile Motion)
Work Energy Power
Forces
Thermal Physics
Gravitational Field
Oscillations

The J2 topics will be confirmed soon!
Please start studying NOW. You could start by dusting off your J1 notes :P

** Note that some of the links are linked to previous SPA practicals so they're not that relevant, but you could just read through to see how it really does apply physically in real time conditions.

Remedial Wk 4

2010-04-13T12:12:00.000+08:00

Remedial this week is cancelled because I stupidly forgot that I had a meeting outside school to attend to. You've all received the worksheets. Complete the structured questions especially, to be submitted on Friday for checking. Will be going through the answers next week!

Then we might move on to Mechanics, seeing that it's quite a big proportion of the next Common Test!

Electromagnetic Induction (aka EMI)

2010-04-13T12:10:00.001+08:00

We've just finished up EMI for the week, so just a short recap and round up of the chapter:

Definitions
I think the more important definitions in this chapter are that of the laws of electromagnetic induction (i.e. Mr Faraday and Mr Lenz are your very very best friends for this chapter). The other two definitions are a little too literal in my opinion but if you happen to be very lucky, the kind where you know the 4D numbers for this week but forgot to buy them then they might just say hi to you during the exams.

So, Mr Faraday likes to say
"the induced e.m.f. is directly proportional to the rate of change of magnetic flux linkage"

and Mr Lenz in reply would say
"the direction of the induced current is such as to oppose the change in flux which causes it"

Do note that Mr Lenz is referring to a case whereby the circuit is a closed one (eg a coil) hence there will be current due to the induced emf that Mr Faraday was talking about. However if the circuit is open then there will only be emf induced and what Mr Lenz is doing is predicting what will happen should we close the circuit. More details here.

Concepts
Flux φ vs flux linkage Φ
Magnetic flux φ = BA cos α
Magnetic fluc linkage Φ = Nφ = NBA cos α

As linkage suggests it means that when there are many many coils, everything links up together hence you have to multiply the flux linkage of one coil with the number of coils present.

Induced EMF

Wire moving in a field: E= BLv cos α (N = 1)
Wire coil moving into or out of a field = same as a wire moving in a field
Wire coil moving within a field (laterally) - the currents will cancel out and there's no change in Φ
Rotating coil in a field E = NBAω sin (ωt)
Spinning Disc in a field E = BAf cos α

"Disturbances within the Force"
Basically things like to maintain status quo. So when anything is disturbed, they tend to resist change and want to return to how things were before. (sound familiar? no? try talking to your parents about them good ol days)

Inducing EMF and resisting change (ie your 5-step guide to answering explanation questions)

So what Mr Faraday and Mr Lenz are essentially saying can be summed up as follows (in the world of EMI):

describe the disturbance (who's disturbing what and in what way?)
state whether magnetic flux linkage has increased or decreased (be specific!)
Quote best friend no 1: Faraday's Law (the increase/decrease ....... leads to an induced emf ....)
Quote best friend no 2: Lenz's Law (this current flows in a direction such as to decrease/increase .........)
which leads to (insert opposite of point 1)

To note:
Remember your angles and your trigonometry! not every question is super nice and straightforward with right angles between everything :)

long time no see

2010-04-08T18:43:00.003+08:00

I haven't had time nor inspiration to write. Lots of things have happened since the promos til now. The holidays happened! followed very quickly by CNY and then *den den den deeeennnn* the common tests (which you've already received by now).

I don't know how you guys feel about your results. I for one am extremely disappointed. If you want excuses for why you've done badly, I can come up with many. but they're just all excuses so I'd rather not go there.

It's time to (as my wonderful ex-captain used to scream in crescendo) "SUCK IT UP!!!!" :)

So if you need, take the rest of the week to whine, then apologise to your parents (because you have no idea how much they love you and how much they're worried sick because you don't ever tell them anything) and promise them that you'll do your best from now on and to ask them to trust you.

Of course you'll have to mean what you say!

Like it or not Common Test 2 is coming up really quick BUT there's still hope yet.
We've got about 11 weeks left so start NOW.

As Barack Obama used to say "yes we can!"

(I'll try to post up more summaries of the other chapters.. do refer to the more recent posts though, cos they would include additions and edits that the older ones might not have..

Oh and remedials are Tuesdays 3 to 5pm. Study/revise/read up before you come otherwise you're just wasting your own time. We're starting with EMI on 13th April)

2010-04-08T10:39:00.005+08:00

http://www.washingtonpost.com/wp-dyn/content/article/2010/03/30/AR2010033004260.html?waporef=obinsite

Dear Mr. President . . .

For a look outside presidential bubble, Obama reads 10 personal letters each day
The black binder arrived at the White House residence just before 8 p.m., and President Obama took it upstairs to begin his nightly reading. The briefing book was dated Jan. 8, 2010, but it looked like the same package delivered every night, with printouts of speeches, policy recommendations and scheduling notes. Near the back was a purple folder, which Obama often flips to first.
"MEMORANDUM TO THE PRESIDENT," read a sheet clipped to the folder. "Per your request, we have attached 10 pieces of unvetted correspondence addressed to you."

Inside, Obama found crinkled notebook pages, smudged ink, cursive handwriting and misspelled words -- a collection of 10 original letters that he considers among his most important daily reading material, aides said. Ever since he requested a sampling of mail on his second day in office, the letters have become a staple of his presidency. Some he immediately reads out loud to his wife; others he distributes to senior staff members aboard Air Force One. Some are from students requesting help with homework; others are from constituents demanding jobs or health care. About half of the letters, Obama said during a recent speech, "call me an idiot."

An interesting look at B. Obama. He's really a nice man.. Just wished his policies were a whole lot more effective.

Have a good break!

2009-10-10T11:15:00.001+08:00

2009-09-14T22:34:00.002+08:00

Point being: Switch off the damn computer and start studying!

A Murder Mystery

2009-09-01T16:14:00.001+08:00

For those who have served on jury… this one is something to think about…Just when you think you have heard everything!! Do you like to read a good murder mystery? Not even Law and Order would attempt to capture this mess. This is an unbelievable twist of fate!!!!

At the 1994 annual awards dinner given for Forensic Science, (AAFS) President Dr. Don Harper Mills astounded his audience with the legal complications of a bizarre death.

Here is the story: On March 23, 1994 the medical examiner viewed the body of Ronald Opus, and concluded that he died from a shotgun wound to the head. Mr. Opus had jumped from the top of
a ten-story building intending to commit suicide. He left a note to the effect indicating his despondency.

As he fell past the ninth floor, his life was interrupted by a shotgun blast passing through a window, which killed him instantly. Neither the shooter nor the deceased was aware that a safety net had been installed just below the eighth floor level to protect some building workers and that Ronald Opus would not have been able to complete his suicide the way he had planned.

The room on the ninth floor, where the shotgun blast emanated, was occupied by an elderly man and his wife They were arguing vigorously and he was threatening her with a shotgun! The man was so upset that when he pulled the trigger, he completely missed his wife, and the pellets went through the window, striking Mr. Opus. When one intends to kill subject ‘A’ but kills subject ‘B’ in the attempt, one is guilty of the murder of subject ‘B.’

When confronted with the murder charge, the old man and his wife were both adamant, and both said that they thought the shotgun was not loaded. The old man said it was a long-standing habit to threaten his wife with the unloaded shotgun. He had no intention to murder her. Therefore, the killing of Mr. Opus appeared to be an accident; that is, assuming the gun had been accidentally loaded.

The continuing investigation turned up a witness who saw the old couple’s son loading the shotgun
about six weeks prior to the fatal accident. It transpired that the old lady had cut off her son’s
financial support and the son, knowing the propensity of his father to use the shotgun threateningly,
loaded the gun with the expectation that his father would shoot his mother. Since the loader of the gun was aware of this, he was guilty of the murder even though he didn’t actually pull the trigger. The case now becomes one of murder on the part of the son for the death of Ronald Opus.

Now for the exquisite twist… Further investigation revealed that the son was, in fact, Ronald Opus. He had become increasingly despondent over the failure of his attempt to engineer his mother’s murder. This led him to jump off the ten-story building on March 23rd, only to be killed by a shotgun blast passing through the ninth story window. The son, Ronald Opus, had actually murdered himself. So the medical examiner closed the case as a suicide.

Taken from here.

Gravitation Equation Summary

2009-08-26T10:09:00.000+08:00

-_-

2009-08-24T15:44:00.000+08:00

When you get two scripts one after another mistaking kinetic energy for 1/2v² rather than 1/2mv². There's obviously some cheating going on here!

Definitions

2009-08-21T09:54:00.003+08:00

Hey hey promos are about a month away! minus away the SPAs and crazy tutorials you're only left with about 2 weeks. scary hor?

You guys will need to work as a class already if possible. Do up summaries to share and start collating your definition list! Split the work up by chapters and get someone to collate everything then zap! As for which definitions you need to know, you can refer to the front of your lecture notes for the syllabus. It's really quite clear.

And with this you can scan through your list just before the exam so it'll be somewhat fresh in your mind. that's a whole lot of free marks for just regurgitating sentences.

Have fun! start NOW.

SPA

2009-08-21T09:46:00.002+08:00

Hey folks

Remember to:

1) Study the summary sheet we gave you especially the parts on the table with the dp etc

2) You should be able to produce a table without much thought by now!

3) When deciding how to manipulate the equation go for the most simple way.

4) Remember that if you want to read off the intercept from the graph you have to make your x-axis start from zero. Not necessary for the y-axis!

(you can cheat by using your graphic calculator to plot where it cuts the graph and then transfer your graph onto the graph paper)

5) d.p for graph refer to previous post. Use the same d.p. for coordinates for the calculations part!

6) Revise through the recent examples for the errors and improvements *coughcoughwinkwinknudgenudge*

That's most of the prep work that you can do. When you do the actual assessment the key is to NOT THINK SO MUCH and just follow instructions :)

Ok good luck everyone!!

SPA SPA SPA!!!

2009-07-22T10:56:00.006+08:00

By now you guys should already be familiar with what you have to do for SPA.
The front few sections (reading instructions, drawing a table for recording data, manipulating the equation etc) should be no-brainers!

Some points to note. Always read ALL of the instructions before you start setting up.

Table
For raw data you should typically have 4 columns with a header row and 6 more rows for recording down your data

Eg for SPA practice 5 we were investigating how time varied with the addition of different masses. So the table would obviously have one column for mass and three columns for time (2 trials and 1 average!)

Please remember that ALL data (raw and processed) has to be recorded!
Raw data has to have same d.p. thoughout the same column and it has to be that of the instrument used to measure it.
Processed data has to have same s.f. as the value that it was calculated from.

Scale and d.p. of graphs
Only scales of 1, 2, and 5 are allowed as shown below

1 box represents 1 unit (there should be 2 zeroes after the first number!)

1 box represents 2 units (there should only be 1 zero after the first number!)

1 box represents 5 units (there should only be 2 zeroes after the first number!)
So your co-ordinates for your gradient triangle has to have the same d.p. as the corresponding axis!

Sources of Error
Please refer to the suggested solutions given to you!
Always (1) explain what was difficult to do physically (2) how it affected the data recorded (3) hence how it affects your plot

Think about
What was important in SPA Practice 4?
What was important in SPA Practice 5?
What was important in SPA Practice 6?

*hinthintwinkwinkcoughcough*

Goals

2009-07-09T10:39:00.003+08:00

Don't mind the onslaught of useless random posts. My mind wanders when I mark your scripts. sometimes I just have to take a break yaknow?

I've had this post tucked away and saved in the drafts folder for quite sometime and I thought it might be an appropriate time to broach on the subject.

By sometime next week (or now even!) you'll be getting back your papers. Some of you would have done awesomely (so give yourself a pat on the back if you can still reach your back) and some of you would have done not so well.

I'm not judging or chiding. I think you're old enough to make personal choices and the choice to study or to play, that was your choice so suck it up and live with it. Am I disappointed with some of you? yes, but only because I believe that you could have done so much better. ultimately you have decide whether to do something about it or not. it's your life and not mine.

At the same time I'd like to say that I was pleasantly surprised and really pleased that some of you put in that last minute burst of effort and did much much better than expected.
Good job kiddos! Just don't pull this kind of trick again ok? not good for my heart!

So anyway, for those that have done not so well, time to sit back and reflect and evaluate.

Did you study your ass off but somehow screw up during the paper?
Do you justify your results with a "oh it's ok I didn't study anyway"?

If you *did* study your ass off, you might be doing something wrong here. check with your classmates, ask them what they did or did not do and then choose what works for you.
It's not the end of the world. There's still a ton of examinations you will have to sit for in your lifetime :)

If you didn't then let's get something straight. If you think you're gonna ace your promos and in turn your A levels, you need to start mugging NOW.
It's not easy to keep up a whole term of work not to mention 3 (promos are in term 4 week 2!!). You didn't prepare for the CTs so you won't know which ideas or conceptions need tweaking or which areas you have to work on more. so you've got a lot of things to do.

My advice to all of you is to reassess your personal goals for the year. It's good to have goals, especially small readily achievable ones.. no matter how silly it may sound :)

Good luck for the rest of the term!
Study hard cos season is no longer an excuse to slack :)

hydropee

2009-07-09T10:21:00.004+08:00

Oh lookie here. this sure looks a lot more appealing than newater innit?

What the 1st Law of Thermodynamics is NOT

2009-07-09T09:59:00.003+08:00

1) energy cannot be created or destroyed....

2) a body is at rest it will continue to stay at rest or if a body is travelling in a straight line it will continue its state of motion unless an external resultant force acts on it

3) if body A is in thermal equilibrium with body B and body B is also in thermal equilibrium with body C then....

SERIOUSLY GUYS?????

but I'd have to say option 2 takes the cake. What the hell did you write for the definition of Newton's 2nd Law in the next question then??

2009-06-01T16:38:00.006+08:00

ok haven't posted anything in awhile cos of the mad rush of tutorials, practicals and marking!

er.. summaries for mechanics, mostly done up last time already, you can probably find the links on the right under the sub-categories. I'll try to post the summary of the test that you guys just took soon.

and 6I and 6C you guys are due in school tmr at 9am and 2pm respectively. we're gonna finish up dynamics 2. make sure you do your tutorials before you come otherwise there's not much point k.

seeya!

In the mean time, study hard!

99 balloons

2009-05-08T13:54:00.000+08:00

Just the Force bit

2009-05-06T10:55:00.002+08:00

Statics

2009-05-05T15:13:00.003+08:00

A force is something that is capable of changing an object’s state of motion.
There are basically two classes of forces: action-at-a-distance forces and contact forces.

In this chapter we look at forces acting on a stationary object. Hence the term "static".
Since the object in question is not moving, we can assume that the object is in equilibrium.

Conditions for equilibrium:
(1) ΣF = 0 - all forces add up to zero/no resultant force/forms a closed vector polygon
(2) Στ = 0 - there is no rotational moment or torque

** special case:
An object acted upon by three non-parallel coplanar forces must pass through a single point if it is in equilibrium.

Hooke's Law
The force F needed to cause an extension (or compression) in a spring is directly proportional to its extension (or compression) x.

F = k x
E = ½ F x = ½ k x²

where k is the constant of proportionality or the spring constant.
when springs are in parallel: k' = k₁ + k₂ + k₃ +....+k_n
when springs are in series: 1/k' = 1/k₁ + 1/k₂ + 1/k₃ +....+ 1/k_n

Fluids
Archimedes Principle
An object immersed fully or partially in a fluid experiences a buoyant force equal in magnitude to the weight of the fluid displaced.

Principle of Floatation
An object floating in a fluid always displaces its own weight of fluid.

An object is said to be floating if it maintains its vertical position when immersed fully or partially ina fluid (except when it is resting at the bottom of the fluid). Hence for an object to float, the upthrust U acting on the object due to the fluid must be equal and opposite to the weight mg of the object.

Free Body Diagrams
1. Always isolate the object you are drawing your FBD on
2. Make sure your force vectors are drawn clearly and separate from each other (reduces confusion)
3. Weight will always act vertically downwards
4. Normal contact forces will always exist when two surfaces touch and the direction is always perpendicular to the surface
5. Friction occurs in the opposite direction of the intended motion of the object

Turning Effect of Forces
Moment of a force about a point
The moment of a force about a point is the product of the force with the perpendicular distance of the force from that point.

Torque of a couple
The torque of a couple is the product of one of the force with the perpendicular separation between the couple.

owe money pay money!

2009-04-24T12:50:00.003+08:00

well ok not exactly.. but you guys owe me a lot of HW!

deadline: Monday 27 April 2009 12pm

10SO6C
Thermal 2 Assignment (tutorial qn 10)
Forces Assignment
Forces tutorial - to submit to me for checking!

10SO6I
SPA teaching lesson 5
Forces Assignment

10SO6M
Forces Assignment

And again, a gentle reminder that I *do* record who does and does not submit their homework. 2 strikes and you get a white slip!

see more Lolcats and funny pictures

Thermal Physics 2 - Ideal Gases

2009-04-15T12:11:00.010+08:00

hokay recap of tutorial!
I think you can handle the energy (internal energy, kinetic energy) part by yourselves, it's mainly just manipulating equations to get what you want ya? :)

Ideal Gas Equation
The behaviour of a gas is affected by its pressure, volume, temperature and amount of gas involved which are related in the Ideal Gas equation. By varying any one of these properties, the other properties will be affected!

Depending on how you perceive the amount of gas (i.e. as individual molecules or as mols of molecules), your proportionality constant will differ as shown above.

n is the number of mols
R is the molar gas constant: 8.314 J K^-1 mol^-1

N is the number of molecules (= n x N_A)
k is the boltzmann constant: 1.38 x 10^-23 J K^-1 (= R/N_A)

Rearranging the equation
If we assume the amt of gas to be a constant (ie n or N are constants) then changing one condition (either p, V or T) will cause the other two conditions to change as well!

Ideal Gas Law with constraints (combined gas equation)
For calculation purposes we express the Ideal Gas Law in the form shown below

Did you know?
All the states of an ideal gas can be represented on a pVT surface as shown below.

taken from http://hyperphysics.phy-astr.gsu.edu/hbase/HFrame.html

It's a tad too complicated to process at this level, hence we usually only focus on plotting p against V .

Mythbusters - How to pancake a car

2009-04-15T12:03:00.000+08:00

coolbeans~

2009-04-15T11:28:00.003+08:00

What happens at absolute zero?
The cold, hard truth of life at -460 degrees

When something is cooled to Absolute Zero (Kelvin), do the electrons and other sub-atomic particles stop moving? Or does "Absolute Zero" only mean that movement stops at the molecular level (as opposed to the sub-atomic level)? - Peter, Someplace, World

I've heard that at absolute zero molecular motion stops. But what happens to electrons, do they also stop? If they do, what prevents them from falling into the nucleus? - William, Austin, Texas, USA

Absolute zero is zero degrees on the Kelvin thermometer scale; it corresponds to about -460 degrees Fahrenheit and -273 degrees Celsius.

Even space isn't that cold. The lingering afterglow of the big bang heats space to 3 degrees Kelvin, on the average. Colder pockets exist. The Boomerang Nebula (at 1 degree K, 5000 light years away) is the coldest known natural spot in the Universe.

We have lowered temperatures of atoms artificially on Earth to almost absolute zero. Atoms near absolute zero slow by orders of magnitude from their normal room-temperature speed. At room temperature, air molecules zip around at about 1,100 mph (1800 km/hr). At about 10 micro degrees Kelvin, Rubidium atoms move at about 0.11 mph (0.18 km/hr) — slower than a three-toed sloth, says physicist Luis Orozco of the University of Maryland.

But matter cannot reach absolute zero, because of the quantum nature of particles. Why this is so has to do with Heisenberg's uncertainty principle (we can never know exactly both a particle's speed and position; in fact, the more precisely we know its speed, the less precisely we know its position).

If an atom could reach absolute zero, its temperature would be precisely zero, which implies an exact speed of zero. But knowing the atom's speed exactly, means we know nothing at all about its position.

"There really is no physical description that allows for [an atom at] zero temperature" emails physicist Erik Ramberg of Fermilab. If an atom could attain absolute zero, its wave function would extend "across the universe", which means the atom is located nowhere. But that's an impossibility. When we try to probe the atom or electron to localize it, then we give it some velocity, and thus a non-zero temperature.

By the way, we can think of an atom either as a particle (a little billiard ball) or as a wave.

As atoms cool to near absolute zero, their waveforms do, indeed, spread out. A waveform as big as the universe seems "weird", but various research groups have cooled atoms to where their wave functions are as big as the inter-atomic distance. When that happens, all of the atoms at that temperature form one big "super-atom," says Mr. Ramberg. This is called a Bose-Einstein condensate.

In 1995 researchers from JILA reported cooling rubidium atoms to less than 0.17 micro degrees K. Reaching almost absolute zero caused the individual atoms to condense into a "superatom" behaving as a single entity. The graphic shows three-dimensional successive snapshots in time in which the atoms cooled and condensed. The false colors appearing white and light blue show atoms at lowest velocities and coldest temperatures. Image courtesy of NIST and the University of Colorado at Boulder.

In 2000, the Helsinki University of Technology lab in Finland, lowered the temperature of a few atoms even farther than the researchers in 1995 — to the coldest temperature yet reached — 0.0001 micro degrees K. But the atoms continued to vibrate, since they were not at (the impossible) absolute zero.

Near absolute zero, electrons "continue to whiz around" inside atoms, says quantum physicist Christopher Foot of the University of Oxford. Moreover, even at absolute zero, atoms would not be completely stationary. They would "jiggle about", but would not have enough energy to change state. In musical terms, it's as if the atom cannot go from middle 'C' to high 'C'. It still vibrates, but cannot change its wave pattern. It's energy is at a minimum.

Further Reading:
Non-quantum explanation of the unattainability of absolute zero by Christopher Foot, University of Oxford
Ultracold atoms and absolute zero, NOVA
Ultra-cold quantum matter group, Christopher Foot, University of Oxford
Bose-Einstein condensation --- what is it?, University of Colorado at Boulder
What is absolute zero? Michigan State University

(Answered April 13, 2008)

Taken from Wonderquest

SPA - Graphing Exercise

2009-04-08T10:36:00.003+08:00

Hey everyone

Please refer to pg 11 of your SPA Guidebook, Part 7 on Examples of acceptable scale markings. You'll have to add in the following zeros as shown in the picture below.

(click for picture to enlarge!)

The new d.p. for scale marking labels are to half the smallest square of your scale. This is because when reading off a graph, that is the smallest to which we can reasonably estimate. Hence your coordinates should be labelled as such!

By labelling your scale accordingly, this will ensure that you record your coordinates to the appropriate d.p. and subsequently your analysis and calculations based on your graph would be accurate.

If you're still not sure how to do the estimate, you can follow the steps below
1) Take the 2 nearest scale markings (must be 2cm apart) and find the difference
2) round off the answer in (1) to 1 s.f.
3) count the number of d.p. after (2)
4) (3) is the number of d.p.s your labels should have

looking for layout designer

2009-04-04T00:00:00.000+08:00

Hey folks

Anybody good at designing blogger templates?
looking to change the layout of this site.

Would like the following stuff:
- two columns are good
- white background (so diagrams can show up properly)
- a bigger column width would be nice!
- auto listing of tags would be wonderful (at the moment I'm using the old template so I have to manually key in all the tag labels)
- er.. space for a poll maybe? and to put random things like pictures etc at the side.

Let me know!
email me -------------->

Thanks much much :D

Thermal Physics 2 - 1st Law

2009-04-03T11:30:00.000+08:00

People, you have got to start listening in class. That goes for all classes - tutorials, lectures, labs etc.

So anyway, stuff we went through this week:

First Law of Thermodynamics

The internal energy of a system depends only on its state; the increase in the internal energy of a system is the sum of the work done on the system and the heat supplied to the system.
ΔU = Q + W

(Note that when defining the first law, you have to include the underlined phrases)

This is one of the first laws you've learnt so far that can be applied to a calculation question. Hence when you attempt any of the 1st Law thermal questions, please follow the standard format:

(start with...)

By the 1st law of thermodynamics,
ΔU = Q + W

(followed by substituting in the values before presenting your final answer)

Note that ΔU depends on the state hence as long as a process involving a move from point 1 to 2, ΔU will be the same regardless of path taken.

Work Done (W) however depends on the path taken as shown below.
The areas under the p-V graph represent the amount of work done in getting from point 1 to 2.

** For cyclic processes, magnitude of net work done is actually the area enclosed by the cycle and there is no change in internal energy (because you go back to the same point!).

Conventions

ΔU positive: increase in internal energy
negative: decrease in internal energy

Q positive: heat supplied to the system/gas
negative: heat is lost from the system/gas

W positive: work is done on the gas (compression occurs)
negative: work is done by the gas (expansion occurs)

Processes & p-V graphs

(1) Isothermal Processes
The shape of an isotherm is as such because, since pV=nRT, when T is a constant and you plot p vs V. You essentially end up with a y = 1/x type of graph.
So what happens when T increases? the "constant" increases so your graph gets transposed upwards. Hence T₁>T₂>T₃>T_4.

(2) Isochoric Process

(3) Isobaric Process
(2) Adiabatic Process

Stuck in my head

2009-04-02T13:19:00.001+08:00

The 29th Council

2009-04-01T15:08:00.006+08:00

Good luck for your council campaigns!

Remember to vote responsibly :)

see more Lolcats and funny pictures

Thermal Tutorial 1 - Common Mistakes for Q1 to Q5

2009-03-30T16:28:00.005+08:00

Q1(a)
The question is asking for the meaning of "two bodies in thermal equilibrium".
So how come so many answers with "it means they are in thermal equilibrium"??

Anyway to explain thermal equilibrium you have to touch on two things
(1) no net heat(or thermal energy) transfer between the two bodies when placed in thermal contact
(2) the two bodies are at the same temperature

Eg of wrong answers:
X no net heat transfer between the bodies and the surroundings
This is only true if the bodies are in thermal equilibrium with their surroundings

Q1(b)
Apologies for this question because I forgot about the part where it relates to the use of a thermometer to measure temperature. So if I cancelled that part, it's supposed to be correct!

Q2
The question is asking about what happens to thermal energy transfer, so when you answer the question refer to thermal energy and whether or not it is transferred, if it is from which body to which?
Also don't forget to include that they have to be in thermal contact, otherwise heat won't be transferred!

Q3
-0.15^oC !!!!!!!!!!!!!

You should mention the following:
- the thermodynamic scale is an absolute scale
- where absolute zero is defined as the "baseline" for no thermal energy
- 0^oC does not equate to zero thermal energy
- hence when comparing how "hot" it is, you'd have to compare in using the absolute scale
- hence it does not equate to "2 times as hot"

Q4(a)
You must explain how the degree of decrease in density is affected by the changes in structure during the phase changes.
ie the amount of increase in interatomic distance for both phase changes which relates to the amount of increase in volume which then relates to the amount of decrease in density.

Q4(b)
Please do not say "something occurs all the time whereas another thing only occurs at this temperature"
It's like comparing apples and oranges.

And boiling does not only occur at 100^oC. this is only true for water.

Q5(b)
generally very well done! :)
Remember to
- explain a little of the kinetic theory (i.e. all the collisions and random motions)
- and then relate evaporation to the escape of the more energetic molecules
- which results in a decrease in the average kinetic energy of the molecules.
- Since average kinetic energy of a substance is a reflection of its temperature,
- a decrease in average kinetic energy results in a decrease of temperature.

Term Calendar

2009-03-25T10:35:00.001+08:00

Hey everyone

The term calendar's been updated. It's a tentative plan BUT there is little room for delays and whatnots, especially since we *have* to finish going through dynamics for tutorial as it will most probably be one of the topics that will be tested in your Common Tests.

It may seem a world away but it's really not!
Add that to Sports Season which is almost in full swing.

Athletes please remember to put in that little effort everyday to catch up on your school work. It's going to be difficult but it all adds up in the end.

Good Luck!

:)

Measurement

2009-03-16T10:41:00.002+08:00

Hey everyone

There's a revision module on Measurement at Discovery@Raffles.
Please log on and try it! there are extra questions in the module too.

ID is NRIC/FIN and the password the DOB in format yyyymmdd.

We'll be logging your process!

2009-03-14T01:42:00.002+08:00

Have a good holiday and remember to do your holiday homework!~

6I, 6C and 6M you owe me questions 1 to 5 of your thermal tutorial by monday 23rd March.

Seeya!

Things to take note of!

2009-03-10T10:03:00.002+08:00

I've marked some of your assignments, and while most of you have got the presentation bit down to pat (Good job! :D) there are still a few of you who seem like you're not even bothering.

see more Lolcats and funny pictures

So refer to posts here and here for the standard of work you should be submitting.

You realise that I repeat this year after year because it really is important.

For qualitative (explanation) questions, try to write in short sentences and to the point. No point in confusing the person marking your script!

Expectations

2009-03-09T14:50:00.005+08:00

Hey everyone

As you all might already have heard, Friday is a holiday cos we did awesome in the A levels.
This also means your class test would have to happen sometime within the next 3 days.

I would just like to touch on some expectations I have for you as students.

I think I shouldn't have to talk about integrity and personal responsibility here but I'll just do it anyway. (you know the whole thing about if you ASSUME you make an ASS out of U and ME thing? yeah..)

I expect that you all as young adults have been well brought up to be honest and good people. Respectful to the right people, polite to most and to one another. Be socially responsible and give your best to everything in which you commit to.

Honestly, your teachers are not going to be disadvantaged whatsoever should you decide to indulge in acts of dishonesty or if you should decide that it's not worth your while to even bother about this test.

It'll just reflect on you as a person, about your character. and really, it adds up in the long run. It will add up in your testimonial, in your recommendation letters as well as your reputation.

What would your teachers say based on your daily assignment/ assessment grades should they be approached for opinions as to whether you would be able to handle academic as well as co-curricular work? would you be up for the job of being in the school team, not to mention the exco of your committee/club/team?

You're committed to getting awesome results come your A levels aren't you? So you should be committed to your studies and this is where you show your commitment. So what if it (lecture tests, class tests, assignments etc) doesn't count to your A levels in terms of numbers and percentages?

I tell you it will count because you want it to count.
Because you have character and take pride in your work and it is a reflection of your best effort.

So think about it if you haven't already :)

Good Luck and Study Hard!

(remember: MUST HAVE PRIDE!)

P/S:
10SO6I - tomorrow (2nd period of your lab)
10SO6C - thursday (2nd period of your lab)
10SO6M - thursday (tutorial period)

If you don't already know, you can check your slots here
(it's the same link as in the right column under "calendar").

If you revise and look through your tutorials again, you should be able to do well :)

2009-03-08T18:26:00.001+08:00

Did you read the papers?
A school girl was sexually assualted near school some time last year.
This is too close for comfort. Please please please be careful. Don't go wandering around by yourself when it turns dark. Always walk out in pairs at least when you're heading home in the evening!!

:(

A-Levels results are out tomorrow!

2009-03-05T10:32:00.000+08:00

Are you all excited yet??????

:D

Raffles Discovery

2009-03-05T10:28:00.003+08:00

The school has an academic portal here.
It has a lot of information and resources for all your subjects eg extra questions and suggested solutions.

Do go check it out!

UsedID: NRIC or FIN
Password: date of birth in yyyymmdd format

Term 1 Class Test!

2009-03-04T10:16:00.000+08:00

Hey everyone

There's gonna be a class test next week on Measurements.
Not sure which period, depends on your tutor.

Please study for it.
Wouldn't it be nice if you could end the term on a nice note with a nice grade to show for it? :)

Good Luck and study hard kids!

'A'levels results come out on Friday. eek :s

Website Recommendation :)

2009-03-04T08:43:00.002+08:00

Hey kids

you should check out HyperPhysics by the Georgia State University.
They have a very large and comprehensive range of resources with very conveniently indexed topics for you to click away!

Have fun :)

T1W8 Tutorial Re-cap: Measurements

2009-02-27T11:02:00.000+08:00

Errors and Uncertainties

For addition & subtraction:

For multiplication and division:

* Percentage uncertainty = Fractional uncertainty in the form of X/100

* Uncertainty = 1 s.f., Magnitude = same d.p. as uncertainty

Thermal Physics 1 - Key Concepts 5

2009-02-26T13:49:00.002+08:00

Experimental Set-up:

*remember to eliminate Heat Loss!

Refer to your lecture notes Pg 12 - 13

Thermal Physics 1 - Key Concept 4

2009-02-26T11:45:00.001+08:00

Experimental Set-ups:

Liquids/Gases - Continuous Flow Method

* remember to eliminate heat loss!

Solids

Refer to your lecture notes Pg 6 - 8

Thermal Physics 1 - Key Concept 3

2009-02-26T10:38:00.002+08:00

Refer to your lecture notes Pg 4 and 10 - 11

Note:
Typical qualitative questions on Kinetic Theory of Matter often asks for how the Kinetic Theory applies to or explains a specific phenomenon (out of the 3 stated above).

a lost generation

2009-02-26T09:41:00.001+08:00

Thermal Physics 1 - Key Concept 2

2009-02-25T10:36:00.001+08:00

Refer to your lecture notes Pg 5

Thermal Physics 1 - Key Concept 1

2009-02-24T12:22:00.006+08:00

Refer to your lecture notes Pg 2 to 3

Measuring Temperature

2009-02-21T11:05:00.002+08:00

(lecture video)

Kinetic Theory of Matter

2009-02-21T11:00:00.002+08:00

(Lecture Video)

Presentation of Written Work

2009-02-20T11:10:00.002+08:00

1) State the Law (if applicable)
2) Write down the equation
3) Sub in your values (follow the s.f. of the values given exactly)
4) Final answer (to the correct s.f.)

e.g.

Re-cap on Measurement Tutorial

2009-02-20T11:07:00.000+08:00

We went through
1) Random vs Systematic errors - know the difference, whether it can be eliminated/reduced and examples

2) Precision vs Accuracy - Identify the degree of precision & accuracy for a given data set

3) S.I. units - 7 base units & how to derive other units

For tutorial in T1W8 please complete the section on uncertainties (2nd section)!

HELLO!

2009-02-20T11:00:00.002+08:00

School has started proper. I've got my timetable as well as all my classes!
and THURSDAYS ARE CRAZY DAYS.
I see all my classes on thursdays so if I come into class cranky I apologise in advance :)

and I'm probably due for a RAM update if there was one available. so 6C, 6I and 6M if you see me around say hi and if I look at you like I've never seen you before in my life just tell me what your name is and which class you're from ya?

By the way I'm lecturing next week, so videos for the lecture will be up asap.

J1T1W1 (actually supposed to be 2)

2009-01-13T13:10:00.003+08:00

OMG school's finally started!
The J2s are going for lessons full swing now.

The J1 teachers are having it somewhat easy at the moment. Meeting after meeting after meeting.... and then there's Open House tomorrow and more meetings to follow for the rest of the week.

*ooph*

Graduation Night 08

2008-12-04T12:27:00.003+08:00

Thanks for the memories kids ;)

:(

2008-11-27T10:50:00.000+08:00

what do you want to be when you grow up?

2008-11-25T10:55:00.002+08:00

"When I was 5 years old, my mom always told me that happiness was the key to life. When I went to school, they asked me what I wanted to be when I grew up. I wrote down “happy.” They told me I didn’t understand the assignment and I told them they didn’t understand life."

not as easy as it sounds but hey, it's worth trying :)

school's out!

2008-11-21T14:21:00.001+08:00

Congratulations on finishing the A levels! :)

2008-11-06T10:20:00.003+08:00

I don't know whether this is a good or bad thing but..
Paper 3 was pretty ~~easy~~ doable right?

but then again, graphs don't really mix well with you guys huh? and definition/explanation questions too.. :/

2008-11-03T22:40:00.003+08:00

Too Cute!

anyway... Good Luck for Physics tmr! :)

Obama vs McCain

2008-10-20T21:43:00.001+08:00

I'm not exactly one for politics, but I *do* love Rick Astley :D

What do you think?

2008-10-15T09:11:00.001+08:00

Some questions that were asked - hope this helps!

2008-10-13T07:57:00.000+08:00

There are 2 situations in which a charged particle in a magnetic field does not experience a magnetic force. State these 2 situations.
(1) when the particle is not in motion
(2) when the particle is moving parallel to the B field

Why can sound waves and water waves go round corners but light waves seem to travel only in a straight line?
This is because the wavelength of sound is physically comparable to the size of the "disturbance" which is in this case a corner. Sound waves are therefore diffracted and hence seems to go round the corner.
Light waves however have a much smaller wavelength and are hence unaffected by a corner which may be 10¹¹ times bigger.

Why can radio waves be polarised but not sound waves?
Polarisation can only happen to transverse waves. As radio waves are not transverse, they cannot be polarised.

Why do we draw stationary waves in a closed pipe (or open pipe) for sound waves as transverse waves when they are actually longitudinal waves?
Since displacement is in the parallel to that of wave motion (sound waves are longitudinal!), it would be difficult to have both variables on the same axis. For transverse waves, since displacement and wave motion are perpendicular, the displacement position graph looks exactly like the waveform of a transverse wave.

So when we plot displacement of the particles against their respective equilibrium positions, we find that they move about a fixed equilibrium position in a to and fro motion.

As such the particles in a sound wave exhibit SHM which is not unlike that of a transverse wave. Hence the displacement-position graph would look like that of a transverse wave which happens to be the same shape as the wave form of a transverse wave.

Consultation Sign-Up Sheet

2008-10-10T11:10:00.001+08:00

I've stuck the consultation sign-up sheet for the next 3 weeks on the table outside the Physics staffroom (the one near the consultation area). If you can't find it it's probably because 2348726553453 students have dumped their bags on said table.

So remember to go sign up if you need to see me for consultation(s)!

Early Decisions

2008-10-10T08:44:00.002+08:00

Hey everyone

I'm gonna stop accepting request for Early Decision recommendation letters by Tuesday 14 Oct. So if you have any you better hurry up!

A walk along the river

2008-10-09T22:25:00.001+08:00

If you're wondering where all of us disappeared to

Latest News about Mock Papers

2008-10-08T08:47:00.001+08:00

The school is only going to print enough for the C, D, E, S, U people so As and Bs are not exactly allowed to come and steal their papers.
However I think that the papers will be uploaded and you are most welcome to download them as well.

wah almost 2 years already

2008-10-06T18:54:00.003+08:00

Study hard k! Last lap already :)

Mock Papers

2008-10-03T09:13:00.000+08:00

Basically for anyone who didn't get an A or a B is required to take the Physics Mock Papers.

I'm pretty sure the As and Bs people are welcome to come and do the paper as well but if you turn up you have to stay for the entire duration ya?

No take-paper-and-run cases ok.

Also, please try to book your consultation slots early.
They come in one hourly slots. I'm not free on tuesdays and weekends. :)

Study hard ya? a few more weeks to go til freedom!

food for thought...

2008-09-30T20:23:00.001+08:00

The Cab Ride I’ll Never Forget

Twenty years ago, I drove a cab for a living.

It was a cowboy’s life, a life for someone who wanted no boss.

What I didn’t realize was that it was also a ministry.

Because I drove the night shift, my cab became a moving confessional. Passengers climbed in, sat behind me in total anonymity, and told me about their lives. I encountered people whose lives amazed me, ennobled me, and made me laugh and weep.

But none touched me more than a woman I picked up late one August night. I was responding to a call from a small brick fourplex in a quiet part of town. I assumed I was being sent to pick up some partyers, or someone who had just had a fight with a lover, or a worker heading to an early shift at some factory for the industrial part of town.

When I arrived at 2:30 a.m., the building was dark except for a single light in a ground floor window.

Under these circumstances, many drivers would just honk once or twice, wait a minute, then drive away.

But I had seen too many impoverished people who depended on taxis as their only means of transportation.

Unless a situation smelled of danger, I always went to the door. This passenger might be someone who needs my assistance, I reasoned to myself.

So I walked to the door and knocked. “Just a minute”, answered a frail, elderly voice. I could hear something being dragged across the floor.

After a long pause, the door opened. A small woman in her 80’s stood before me. She was wearing a print dress and a pillbox hat with a veil pinned on it, like somebody out of a 1940s movie. By her side was a small nylon suitcase. The apartment looked as if no one had lived in it for years. All the furniture was covered with sheets. There were no clocks on the walls, no knickknacks or utensils on the counters. In the corner was a cardboard box filled with photos and glassware.

“Would you carry my bag out to the car?” she said. I took the suitcase to the cab, then returned to assist the woman. She took my arm and we walked slowly toward the curb. She kept thanking me for my kindness.

“It’s nothing”, I told her. “I just try to treat my passengers the way I would want my mother treated.”

“Oh, you’re such a good boy”, she said. When we got in the cab, she gave me an address, then asked, “Could you drive through downtown?”

“It’s not the shortest way,” I answered quickly.

“Oh, I don’t mind,” she said. “I’m in no hurry. I’m on my way to a hospice.”

I looked in the rear view mirror. Her eyes were glistening.

“I don’t have any family left,” she continued. “The doctor says I don’t have very long.”

I quietly reached over and shut off the meter. “What route would you like me to take?” I asked.

For the next two hours, we drove through the city. She showed me the building where she had once worked as an elevator operator. We drove through the neighborhood where she and her husband had lived when they were newlyweds. She had me pull up in front of a furniture warehouse that had once been a ballroom where she had gone dancing as a girl. Sometimes she’d ask me to slow in front of a particular building or corner and would sit staring into the darkness, saying nothing.

As the first hint of sun was creasing the horizon, she suddenly said, “I’m tired. Let’s go now.”

We drove in silence to the address she had given me. It was a low building, like a small convalescent home, with a driveway that passed under a portico. Two orderlies came out to the cab as soon as we pulled up. They were solicitous and intent, watching her every move. They must have been expecting her. I opened the trunk and took the small suitcase to the door. The woman was already seated in a wheelchair.

“How much do I owe you?” she asked, reaching into her purse.

“Nothing,” I said.

“You have to make a living,” she answered.

“There are other passengers”.

Almost without thinking, I bent and gave her a hug. She held onto me tightly.

“You gave an old woman a little moment of joy,” she said. “Thank you.”

I squeezed her hand, then walked into the dim morning light. Behind me, a door shut. It was the sound of the closing of a life.

I didn’t pick up any more passengers that shift. I drove aimlessly, lost in thought. For the rest of that day, I could hardly talk. What if that woman had gotten an angry driver, or one who was impatient to end his shift? What if I had refused to take the run, or had honked once, then driven away?

On a quick review, I don’t think that I have done anything more important in my life.

We’re conditioned to think that our lives revolve around great moments. But great moments often catch us unaware - beautifully wrapped in what others may consider a small one.

By Kent Nerburn (Reproduced with kind permission).

Kent Nerburn is the highly acclaimed author of eight books on spiritual values and Native American themes. This beautiful story has been widely circulated on the web. It originally appeared in Kent’s book Make Me an Instrument of Your Peace

ugh.

2008-09-23T15:06:00.002+08:00

7 more classes to go as of now.
haven't gotten back any of my classes yet.

Paper 1 was not too bad despite 40 questions as opposed to 30. May have something to do with the fact that one wrong answer only costs you 1 mark instead of 2.

No idea how everything's gonna add up though. It's different from the last cycle so we'll see..

Calendar

2008-09-22T10:06:00.000+08:00

By the way, I've posted a link on the right to a school calendar that I set up.
Please refer to it if you're not sure whether you're supposed to turn up for school on certain days.

The A level timetable will not be put up because I'm not that free.

So remember to turn up for school this friday!
6T bring your Paper 1.

Thanks!

Paper 3

2008-09-18T09:31:00.001+08:00

How was it?

Harder than Paper 2?
or was it just Section B that killed you?

I haven't started marking Paper 3 yet cos someone is hiding 6T's Paper 2 from me. and that's my last class to mark for Paper 2. *rawr*

Paper 3 Reminders!

2008-09-16T11:29:00.002+08:00

There is a compulsory Section A, in which you have to do ALL the questions there.

As for Section B you will have to chose two 20-mark questions from that section to attempt.

Please read through all the parts for all the questions in Section B before deciding on which questions to do, because it will be a big waste of time if you are halfway through a question and you realise that you're stuck.

Good luck!

mid-marking madness

2008-09-15T15:13:00.002+08:00

Let me just give a few words of advice..

Keep everything to 3 s.f. if you're not sure or are prone to s.f. errors!

Also, 0.200 m is not equal to 200 cm

(so obvious which question I'm marking right?)

Oh and the last part actually asks "before or after"
so technically there are only two options ya?

Happy Mid Autumn Festival!

2008-09-14T23:03:00.003+08:00

I remember one year my room mate had a paper lantern in the shape of Bubbles from the Powerpuff girls. I was so jealous can!
anyway we went out to have a mooncake picnic in the gardens with our lanterns and Bubbles got her hair burnt! That was scary. So moral of the story is be careful with your lanterns ya?

Or you could just buy the ones that need batteries..

But as we all know it's the middle of the Prelims and you all have to mug/cram/etc. Always good to took a little break tho, and revisit your childhood with a little mooncake, tea and lanterns!

or maybe just a little walk outside with a peek at the moon and maybe you'll be able to spot the bunny trying to escape the moon's G-field ;)

Paper 2

2008-09-14T13:51:00.000+08:00

How did you all find it?

So far I've come across a lot of SF ERRORS. whhhhyyyy? :(

the "GOD" particle

2008-09-11T15:26:00.006+08:00

Large Hadron Collider activated successfully!
"The LHC will send beams of subatomic particles called protons whizzing around the tube at just under the speed of light.

The hope is that they will smash into one another and explode in a burst of new and previously unseen types of particles – recreating on a tiny scale the heat and energy of the Big Bang that gave birth to the universe 13.7 billion years ago.

The experiments could confirm the existence of the Higgs Boson, also referred to as the "God particle", the Higgs Boson could help explain how matter has mass."

this is too cool heh

Recommendations

2008-09-09T10:23:00.010+08:00

I understand that a number of you will be applying overseas (mainly to UK and US) and would be requiring recommendation letters.

If you would like me to write you one, you will need to

1) ~~beg and grovel~~ Ask really really nicely

2) Provide all the necessary forms and envelopes
(if anything is missing or there's too little credit for postage stamps I'm just gonna send it as it is)

3) have a summary sheet as follows:

4) Include information about yourself
(ie your portfolio, 3 best achievements, whatever reflections you've done or peer evaluations that your friends have wrote for you.)
This is to facilitate painting a better picture of you for the recommendation.

5) Submit all this by Term 4 Week 5 Thursday 9 November 1230pm.
That's 2 weeks after the prelims for you to get your act together ya? Get it over and done with and you can concentrate on your A levels.

Of course before you start to think about all that stated above, please be honest with yourself and think about whether I will have anything nice to say about you.
If there's nothing good to say, then there's nothing to say. ;)

oh and another thing. I don't like being harrassed. So before you send out that sms, READ IT AGAIN.

2008-09-01T22:22:00.001+08:00

hey everyone

thanks for all the well wishes and the gifts :)

k now study hard and good luck for the upcoming prelims! :)

by the way..

2008-08-21T19:33:00.001+08:00

How come nobody noticed that there are 2 girls being nominated for Dance King?

Circular Motion Revision Tutorial Q5

2008-08-21T09:06:00.008+08:00

The graph of a gymnast swinging around the horizontal bar should be as follows:

The previous graph that was presented to you in class is assuming that (1)the gymnast is gripping the bar very lightly (2)the gymnast only starts to pull/press on the bar after passing the horizontal position

In reality this doesn't happen, and usually the pulling/pressing of the bar happens before the gymnast becomes truly horizontal.

The graph above also makes the assumption that gymnast doesn't have moment of inertia. We're simplifying the situation by treating the gymnast as a point mass m and connected to a pivot via a massless rod.

(Note that this is different from a mass connected to a string undergoing circular motion. Strings can only undergo tension! so it's not valid for this example.)

Resultant force:
Conservation of energy:
Find an expression for F and then F_v = F cos θ
Solve for values of θ
and also the minimum points (differentiate and equate to zero).

This derivation can be found in full on discovery@raffles.
It is not in syllabus and is strictly FYI only.

discovery@raffles

2008-08-19T08:11:00.001+08:00

Hey everyone

there's lots of stuff on discovery@raffles.
Please go log on and see.

:)

Make-up Tutorial anyone?

2008-08-18T14:58:00.001+08:00

Would you guys be interested in a make-up tutorial for E Field/EM/EMI that was scheduled for next week but most likely will not happen?

I'm thinking Thursday 28 August say 10am to 12pm?
Leave a comment with Name and class so I'll know whether or not to book classroom or small LT.

lemme know!

Google Maps

2008-08-12T11:31:00.003+08:00