Since secondary physics is where you left off, I think reading an A-level book would be appropriate as it isn't too hard to understand. If you'd want to get something short, I would suggest reading 'Longman Advance Level Physic' by Loo Kwok Wai (Longman). If you would like something deeper try 'Physics for Scientists and Engineers' by Raymond A. Serway that can be found at our uni library (location: QC23 SER f). Personally, I found those books easy to understand and interesting. All the best!

Edit: Grammar

This post has been edited by Thinkingfox: Jun 18 2009, 02:09 PM

Feynman? I thought this dude.

Hmm. I'll look around for it. Thanks for the heads up.

Lol! Thanks! Nice, there's even the code to look for.

hi, doing my 2nd year physics,
rite now doing newtonian and relativistic and wave vibration and circuit.

Hey, I am a form 5 student.Can I ask my doubt here?

NO!! Only those with PhD in Physics and above can discuss!

Oops. I don't have a PhD in physcis. So even I can't discuss...

LOL..Just kidding, dude. This discussion is open to everyone of all levels. Of course some background reading would be encouraged.

waoh... i am so tired now....
just back from a trip promoting theoretical physics to secondary school studetns...
it is always good to see response from students. well, except for one chinese school which is so damn stupid.

Damm, why weren't you around during my years as secondary school student .... wish that i had exposure to it back then

What happened?

lol, reminds me when there was this one professor, doing bio thingy.. not sure about what, forgot edy.
she came and explain stuff..

It's not up to me also. But I am the first few person to initiate this project.

A bunch of form sixers all totally non responsive to any of our questions even though we already tried our best to communicate with them.

You what's the funny thing? A form 1 boy who happened to be at the venue actually respond to us and asked question which is actually a good question.

This is totally ridiculous. A group of form six students who are studying in a prestigious school are worse than form 1 kid.

on the other hand, matrikulasi is 100x better.

Last time i used to think matrik students are worse than stpm students. Now? Totally opposite view. (i am stpm dude)

I'm now just started Form 6 last month...any ideas how do I understand more on how to solve various linear motion problem[As what I learn the most for now is all linear motion] cause always got so many forces acting on a certain objects, and I'm kinda confuse with Newton's 3rd Law of Motion which is about Action = Reaction, its like when the question as me the helicopter fly up, they give me the G[Acceleration due to gravity], and mass, then they ask me how many force produced for the helicopter to fly up..then i try to relate it like the force pulling the helicopter down should be equal to the force requred for the helicopter to fly up...but at the same time, i think that the helicopter should have high upthrust force if they want to go oppose the gravity...bu the answer turn out to be the force required to go up = to the weight...why i find it confusing


Anyway, I love Science since primary school and was science top scorer till form 3, and in form 4 and 5, my top subject was physics followed by chem and bio...i love physics so much that I often ask teacher a lot of questions but they hardly can answer any of my questions >_<I always took up some read in the internet but also kinda hard for me to understand >_<

And yeah, I got offer for Matriculation, but then i finally choose to go form 6 although they say much harder than matrikulasi, but the main reason for me to go form 6 is bcoz i get to study deeper in science subs especially physics and chem compare to matriculation bcoz i am very interested in physics and wanted to learn more although it is ahrd

This post has been edited by -Max91-: Jun 19 2009, 09:21 PM

Haha it's common to misunderstand what the 3rd law is saying. I hope this helps.

The simplest and the most accurate way of stating the 3rd law is "If body A exerts a force on body B, body B will exert the same magtitude of force on body A" Sounds easy but not easily understood when its used to solve problems.

Take the helicopter as an example. The earth pulls the helicopter towards it and by virtue of the 3rd law, the helicopter MUST pull the earth towards it. Because we are dealing with gravity, the universal law of gravitation applies here and these two forces are N3L pair forces. Sounds easy right? However this is where many people get confused, I quote,


Can you see where you got lost? There is a engine thrust that acts upwards and there is a helicopter's weight pulling downwards and you made them equal. This is wrong because N3L doesn't come into the picture. Think about it, the helicopter's weight is due to the gravitational force exerted by the earth on the helicopter, so which is its corresponding pair force? Shouldn't it be the gravitational force of the helicopter exerted on the earth(helicopter pulls earth)? The thrust is not the corresponding N3L pair force. It's just another force acting on the helicopter in addition to the gravitational force. A N3L pair force must be the same species, I pull earth, earth pulls me, same species of force.

Now then what is the corresponding pair force for the thrust? The engine pushes the air downwards, so what pushes the engine(helicopter)?

The way to solve such problems is to draw free body force diagrams, it's essentially a diagram that shows you what are the forces acting on the body. N3L does not apply here. Why? Just read the 3rd law again. To give you a hint, if I exert a force on a body, I don't feel, I don't experience the force exerted by me. I don't feel my own push when I push someone.

Does it help?

This post has been edited by feynman: Jun 20 2009, 03:50 PM

Erm thanks, kinda get it, so i think it would be the air push the engine upward...and I don't feel the force when i pushing at something because an equal force is pushing at me too..is tat right?

But still one thing not really clear, from previous question, if the helicopter want to take off, so to get the acceleration or velocity or watsoever, i juz have to equate it with the engine trust but not weight?

You do. Newton's 2nd law says: Resultant force = rate of change of momentum of the object

So it's actually upwards thrust - weight = dp/dt (rate of change of momentum)

omg, thanks a lot, totally understand about it....i always too remember the general formula F=ma but i always forget tat the ma was actually rate of change in momentum, that's y i couldn't solve it

one more question, normally in what cases we use newton's 3rd law? cause most of the question always ask on resultant force which the 2nd law can solve almost everything, so far the 3rd law i did was a truck pulling a car, or box and box stick together and force is exert on them >_<

thanks

er..my physics is not that bad..can score 90+/100

p/s.all discussion here about uni level? seem like we do not learn deep for newton 3rd law.I think I should not study it to confuse myself..haha..meybe syllabus different

hi, just started my foundation with physics in my sub. didnt touch this topic for 3 years since SPM. is there any reference book for a pre-u studies?

can you help me this doubt?
why is it U shaped one the magnetic field strength stronger?

another ques




thanks

This post has been edited by vick5821: Jun 22 2009, 07:47 PM


Attached thumbnail(s)

About U-shape, i think the text in the second picture you post explains it. More magnetic flux concentrated in an area.

but i dont understand what is meant by it