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

kenloh, actually your calculation is not wrong. it is part of the solution if you treat the problem as 2 parts.

first part would be travel against gravity from 0 position back to 0.
second part would your 1.385s where the ball travel from 0 to 65m with the help of acceleration.

first part should give u solution of 8.xx seconds.
add up with second part and you will get the final solution.

I also got the answer as 9.570. I can only say, doing physics need exercise to sharpen you mind. It is important to read more books to have new ideas. University level physics can be very tough for normal secondary school students. However, i also found that today secondary school physics seems become to lack of theory. I can even no need to prepared notes to teach my tuition student. IN physics, the concept is the most important part. with one concept right, you can solve many question.

ive fully understood wat u guys r saying,i misinterpret the question wrong thats y i got -9.57 instead of a positive value,i put it as throwing 35degrees down instead of throwing it up

question solved and completed.

This post has been edited by kenloh7: Sep 15 2009, 12:06 PM

I have a thought experiment that i am too lazy to calcualate.
We all know that light speed for an object is quite impossible becuase it requires infinite energy. But here is the question.
There are 2 objects (spheres) in a vaccum.

Object A has a mass of 1Kg and is 100m away from object B, object A has a radius of 0.01m.

How much mass/density does it require for Object B to be to attract Object A so that Object A will accelerate to 99% or 100% (if possible) of light speed before it crashes into Object B.

I have a fairly reasonable idea on how to solve that problem simply by using Newton's law of universal gravitation and some linear kinematics, however I am far too lazy to do the math. Whatever the result, I still don't think it'll be what you're looking for, because when we're talking about speeds near the universal limit we'd have to rely on Einstein's general relativity, which is way beyond my grasp. So perhaps I shouldn't have said anything at all. Funny how that works out.

This post has been edited by pixelsheep: Sep 17 2009, 01:44 AM

hello,i'm new to this discussions.but hope i can join in since it's interesting.i'm doing master in physics in local U.i must admit i'm still in very basic level of physics.
come on,physics is all about basic what.
nice to meet u ppl.

---

Added on September 29, 2009, 11:43 amMaggieMee, abt d sphere experiment.
"I have a thought experiment that i am too lazy to calcualate.
We all know that light speed for an object is quite impossible becuase it requires infinite energy. But here is the question.
There are 2 objects (spheres) in a vaccum.

Object A has a mass of 1Kg and is 100m away from object B, object A has a radius of 0.01m.

How much mass/density does it require for Object B to be to attract Object A so that Object A will accelerate to 99% or 100% (if possible) of light speed before it crashes into Object B."

by newtonian physics,
mass of B = 4.5e31 kg if it collides in 1 nanosecond.aprox to mass of sun.
funniest part is mass of A is not used in the calculation.correct me if i wrong.
if got time,i'll try to fuse relativity in it.
nice thought experiment it was.


This post has been edited by freeman_86: Sep 29 2009, 11:43 AM

Hi All!
Physics graduate here.

hope this place doesn't turn into a "help me solve my homework" forum. haha

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?

We learn this in high school haha... Correct me if i'm wrong, natural frequency is simply the frequency that every physical being vibrates at. It's different for every thing. I'm not too sure what happens when resonance happens like that. I think it'll disturb the vibration or something and the thing breaks. Like an opera singer who cracks glass. Google it

This post has been edited by pllx: Sep 29 2009, 09:32 PM

Erm, natural frequency is the frequency of which when applied to an oscillating object, it will oscillate at its maximum 'swing' i.e. maximum displacement.

try not to confuse forced oscillation, which is when u exert external force onto the oscillating system (which may displace it more than the maximum displacement via natural frequency)

anyway, needs verification.. basing of what i've learnt, for like >5 years ago?

can anyone tell me what is quantum mechanic actually?cut the jargons.
tell in common words so layman also can understand.tq.

XD the term mechanics itself is rather difficult to understand ady.

Google helps



Mechanics pertains to the understanding of how things work. At least by definition.

This post has been edited by ZeratoS: Oct 5 2009, 02:49 AM

quantum = atomic/subatomic level
mechanics = mechanism study, like how thing work, why thing won't work

quantum mechanics, in layman explaination, is the study of the behaviour of mass, at atomic/sub-atomic level. It study the behaviour under various condition, configuration, external disturbance, energy level, etc....

It's like study of car behaviour, different engine, different chassis, different fuel, different tire, suspension, and when accelerating uphill, downhill, taking a corner, collision (accident) etc... but everything at atomic/sub-atomic level.

ermm, i need some explaination about knematics theory and some example of it. i search everywhere but i cant get it. its involved in mechanicals action right.

for some reasons those physics students are all gone , I think you might need to wait some time before a physics student stepping in to answer your question

Because the whole section have been filled up with crap.

Lol, there is an apparently an unconfirmed study that suggests that 80% of Malaysia's workforce has only reach up to the SPM level of education, the rest of the 20% are either almost invisible to sight, or have left to a more intellectual country.

This post has been edited by Deadlocks: May 30 2010, 12:10 PM

there were quite a lot of physics students a few pages back but they vanished without a trace
maybe im the one to blame
been posting purposeless comments here , but i promise i'll post comments with content next time

This post has been edited by ComposMentis: May 31 2010, 12:26 AM