Pascal's Principle

If u watch the above video, some people in this world were having fun without realizing that they should be grateful to a well known French scientist named Pascal. Without his discovery theirs life will not be exciting enough.This jumping car is actually applying his principle `that being widely used in a hydraulic or pneumatic system. I'm not gonna discuss how the car can jump, but i will discuss about the fundamental principle used which allows the car having this 'hip hop' movement.
Ok..lets get back to our SPM discussion on another important physics principle i.e the PASCAL's Principle.
As usual, in every physics principle, u must be able to state the principle itself...
So what is Pascal Principle????

Pascal principle states that:
Pressure appllied in a confined liquid is transmitted uniformly in all direction through out the liquid.

..to those who dontt undrstand the word 'confined liquid', take out a dictionary & apply its meaning in the context of this principle. Basically in B.M it means.."cecair yang berada dalam bekas tertutup".

So if the liquid is trapped in a container and pressure is applied, according to the principle; this pressure will be transmitted equally in all direction.

If u watch above diagram..according to pascal principle, all the water that moves out from the holes received the same pressure.

Now lets analyse this interesting activities carried out among some students in this video.....from the video,can u explain why the glass breaks at the bottom part of the bottle???



Pascal principle is widely used in a hydraulic system. In SPM its a must for u to fully understand the application of a hydrauick jack, hydraulic brake & etc. There's some simple calculation involved.
Watch this!!



Usually the input piston has smaller area..bcoz when area decrease the pressure applied will be multiplied even if u press it with a smaller force. So this huge pressure will be transmitted equally to the output piston. Thus a bigger output force is produced at the larger piston.This explains the reason why the boy who is standing on the input piston can lift up the car.

How to derive it;s mathematics relationship ??
Ok..first u must notice that ..
Presure applied in input piston = Pressure transmitted to output piston
                                       P 1 = P 2
Thus,                          F1 /A1 = F2 /A2              

(Referring to the video, the boy's weight represents the F1)              

Principle of Conservation of Energy

Another important physics principle that we learned in SPM is Principle of Conservation of Energy. In form 4 we've learned about these following energy;

i. Kinetic energy - energy due to movement ( 1/2mv^2)

ii. Gravitational potential energy - energy due to height or position of an object (mgh)

iii. Elastic potential energy - energy stored in an elastic material (1/2Fx)

iv. Heat energy (Q=mc@)

Meanwhile in form 5 u'll be learning the following energy:

i. Electrical energy (E=VIt)

ii. Nuclear energy

Ok..all these energy that u've learned will obey a physics principle called conservation of energy.

So what does this principle tells u??

Principle of conservation of energy states that;

1. energy can't be created or destroyed by human

2. energy can only be transformed from 1 form to another
3. total energy during the transformation is constant
Look at this video...

Statement 1 & 2 mean  we as human can only managed to transform those energy. For example a rotating fan transformed electrical energy into kinetic energy & some might escape  into heat.

Then applying statement 3, it means.. total initial energy= total final energy...

therefore...

 total electrical energy supplied = total of kinetic energy used + heat energy

In other words those energy trasformed in a rotating fan is conserved. If u noticed, the fan might cause some heat lost due to friction in its motor. So this heat is a wasted energy. By right a function of a fan is to rotate & let us feel cooler, not to make us sweat by releasing heat :)  .. If this is the case, we can say that the fan has some inefficiency in its job. 

Due to this reason we came across in a concept used to measure energy efficiency. 

Energy Efficiency = (output energy / input energy)  x 100

Efficiency's calculation is about getting the percentage. If we refer to case of the rotating fan again,  electrical energy supplied to the fan  is the input energy. Meanwhile the kinetic energy acts as its output energy. So by calculation,

Efficiency of the fan = [(Kinetic energy used) / (Electrical Energy) ] x 100

Let say from the calculation  its energy efficiency is about 80% . So mana pergi the balance 20 % ???? 

This is because 20 % of the energy has been wasted into heat. 

In real world its almost impossible to get a sytem or device that works 100% efficient. Even u as student  are not 100 % efficient :) ..Of course i will prove it to u...

• Let say in physic's exam, total given marks for paper 2 are 100 marks (i.e the input). 
• What u've answered correctly represents the output.
• Usually your output is less than 100 marks, or even worst whuch in some cases u dont even get more than 50 marks. 
• Thus your efficiency will be around 40 %. 

If thats the case, u should asked yourself mana hilang that 60% ?? .. u should keep asking what causes you to be so inefficient??? Identify those culprit that threatening u from becoming an efficient student....
Is it due to 'cinta monyet' things, or attitude problem?..or is it bcoz most of your time wasted due to your addiction towards internet unwanted activities such as too much social networking, gaming or pornography??? 

Once u've figure it out...i sincerely advice u to make a change b4 its too late   ..who knows with some attitude transformation u might be 90% efficient in November 2010. If u managed to do it..i'm pleased to say that an 'A+'  is within your grasp.

To summarize our today's discussion on conservation of energy, i highly recommend u to watch these videos..
Enjoy your revision ;)

Happy Teacher's Day

“The mediocre teacher tells. The good teacher explains. The superior teacher demonstrates. The great teacher inspires.”
 – by William Arthur Ward
..Selamat Hari Guru untuk semua warga pendidik ..

Bernoulli Principle

Another important physics principle in SPM is Bernouli principle. For those who hates doin physics' calculation, Bernoulli will be a gud news for u coz no formula is involved at this stage. However u really need to grab a genuine understanding on its concept.

Ok..what is Bernoulli Principle ??

In simple words Mr Bernoulli stated that..
"if the velocity of fluid increase, the pressure decrease"...

Bernoulli is one of the fascinating physics principle & yet it's easy to understand..it relates the effect of fluid velocity on pressure.
..if u notice, the term fluid is used just like in Archimedes..
just to remind those yg dah lupa, fluid means 'benda mengalir' i.e it can either be air (gas)or liquid.

Common mistakes among students, they always think that pressure causes the increase in velocity. In fact it is the movement of air or liquid velocity that causes the change in pressure.

Here some cool & interesting lectures which i collected from the net. If u understand nothing on bernoulli,you must watch these videos to clear the air :)




Besides knownig the principle, in exam u must be able to apply and explain the bernoulli effect on venturi tube, floating ball, water sprayer, aerofoil etc.
Lets analyse the video about water sprayer below..can u explain why the water rises ??


Another interesting facts about bernoulli, it allows an aeroplane gain its lift force from the wing's aerofoil shape. If u intersted to further study in aerospace or aeronautical engineering, u need to fully understand the working principle of an aerofoil.
Look at this video..even this cute little girl can explain the aerofoil concept.. i think u should be ashamed of yourself if u r still too lazy to think about it ;)



To understand what causes different water level in venturi tube is also important aspect in bernouli principle. It always being asked in the exam. U need to fully understand & be able to explain the change in water level.
Who knows it might come out in this year SPM...so apa tunggu lagi, get your book & revise them now!!! :)

Archimedes Principle's Application

Learning the application part of each physics principle is a must in SPM. You must know the working priciple of each application. For example in archimedes principle, you should know how submarine can float & sink. Then u must be  able to explain it by using relevant physics concept. This kind of question will always being asked in paper 2.

If u really wanna get an A, u must learn all the physics application. For this reason i 've selected the following clips for u to revise on archimedes's application. Some of these videos only gave u a general idea on the practical aspect of the application. U need to refer a physics book to fully understand how each application works. So please make sure u have your reference book next to you while watching these videos...enjoy your  revision :)

Examples of Archimedes' application:

1. Plimsoll line

2.Hydrometer

3. Submarine

4. Cartesian diver