Physics 23 Nov 2013?

[WYuMon]

How was it guys?

 

[Muhammad Haris Ghani]

How was it guys?

awesome

 

[WYuMon]

Same for me!
Whats your ratio potential/kinetic?
I got 3

 

[Sapphire]

0_0 i got 1:2

 

[Jacob Park]

i got 1/2 as well !

 

[WYuMon]

Oo thats odd my friend got 3 too
Anyone remember the question?

 

[Jacob Park]

Wasn't it a ratio of potential energy/kinetic energy when a ball is at maximum height/2

 

[WYuMon]

Yeah at 1/2t the distance is halved but not the speed
I remember using formula v=u+at to find speed at 1/2t
its mgh/ 1/2mv^2 right?

 

[Jacob Park]

What I did in the exam was using energy conservation law.
When h is halved, gravitational potential energy is halved. Therefore, since I knew total amount of energy by calculating kinetic energy at the first part of the question, I just subtracted the gravitational potential energy from the kinetic energy. As a result, I got 1/2 ratio.

 

[WYuMon]

I dont know, I used kinematics way
Redo the question I still get same ratio
Initial velocity is 16 m/s
Time taken to reach max height is 1.63s
Max height reached is 13m
How about yours?

 

[Jacob Park]

Wait a minute, haha I think i got 1 for the answer which seems to be definitely wrong as i looked at it now, damn.

 

[panpan101]

1 might be the correct answer. Thats what my friends got

 

[Jacob Park]

wat u got?

 

[WYuMon]

1 for the ratio? How about the time and maxheight reached?

 

[panpan101]

I didnt get anything cause i dont take physics... sorry but i asked my friends and they got 1... some of them