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

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?

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

Ya basically all the physics learn during secondary school is exam-orientated..juz teach u how to score..but not really try to create an interest in physics among students

I got 9.57s wor >_< not sure mine correct a not also

Orh, this is my school Physics Teacher's method >_<
1st, always divide into two components, X and Y

So in this case, since we don't know the displacement(For X), but for displacement(Y), we get is -65m.[Note : I put a negative in front, because the object is projected from a building which is 65m tall, therefore, the final DISPLACEMENT for Y-component is 65, include ngative because it is going in opposite direction]

Then, since you got displacement(Y) = -65m, acceleration,a = -g (Must put negative, because your motion is opposing the acceleration due to gravity) and velocity(Y-component) is 70sin35. Therefore, sub all these value into :-

s = ut + 1/2at^2 [For all Y-component only]


Sorry can't provide you an image, but if you still don't understand I'll draw it out and scan into my com >_<

This post has been edited by -Max91-: Sep 14 2009, 11:03 PM

Erm now I'm learning Resonance, but there's a problem here...what does Natural Frequency actually is? I don't really understand..does it have a value or what? and is the value fix or change?