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OCR Physics A G481 Mechanics [Thursday 17th May 2012]

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Reply 100
Original post by JohnSimmons
Did you work use SUVAT to work out displacement? Then put that into work done is force x distance? Then divide by time?

That's what I did but I cant remember my answer :\

Also, what was the answer to the previous question. The one where you had to work out the force of the spring or something?


i did that...but i thought you divide the time by 2 coz ur working out half the distance??? i dunno....i was not very confident with it....
When both rockets A an B are on, the forces are equal so there is a torque which produces a turning force/rotational force- so it rotates?
When just A is turned on, the net force favours the direction of A since A>B. I think?


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Original post by stackemup
Yes so happy, took me quite a bit of working, but I got 2.6 as well.

Damn, that 5 mark deforming solids qualitative question took the absolute p***.


could you remind me what question was this? cant even remember!
Original post by blackhole
could you remind me what question was this? cant even remember!


It was a glider and a spring. You had previously worked out the force. You are then given a time of 0.094 seconds (I think) and are told to work out the rate of work done.
Original post by blackhole
could you remind me what question was this? cant even remember!


Well there was a spring with force constant 50 and was compressed by 0.07 metres. The time the force was applied for - or something like that - was 0.094 seconds.
Really interested as to how everyone got 2.6 as i could not do this question for the life of me!
Reply 105
I messed up this exam.
Wasn't the energy stored in the spring 1/2kx^2
So the energy stored was 0.5 x 50 x 0.07^2 = 0.1225 j
So energy done per second is 0.1225 / 0.094 = 1.30

I left my answer as 1.30 so I must of missed something... but oh well.
Reply 107
sooo not looking forward EWP...
I got 2.6 but just realised its 1.3

I did work done/time

So I did the force x distance / time

However work done for a spring is area under a graph

So its half the force times distance / time which is 1.3

Bugger
Reply 109
Original post by JuxtaposedJames
I got 2.6 but just realised its 1.3

I did work done/time

So I did the force x distance / time

However work done for a spring is area under a graph

So its half the force times distance / time which is 1.3

Bugger


crap! i did the same thing...
Original post by striver17
crap! i did the same thing...


I think everyone did as everyone thinks 2.6 is the right answer...
Reply 111
can someone please make an unofficial markscheme???
Reply 112
Original post by Butterkist123
I thought the angle was 31 not 59. Because it went 30 up and 18 across..not the other way round.


Yeah, I agree with you. I got 31 too...
Original post by sarah-xx
Yeah, I agree with you. I got 31 too...


Me too :biggrin:
31 is wrong.. :'( apparently it said between horizontal
Reply 115
Original post by emah123
can someone please make an unofficial markscheme???


If somebody has the paper I will make an unofficial mark scheme, I can remember most of the questions and answers but I really don't want to do a MS without the paper tbh, I got around 53-54/60 Which should hopefully be 90+ UMS I would suspect based upon previous boundaries.
Who gets access to the paper after we've done it? Is it only teachers?
What do people reckon full ums boundary and A boundary will be

from answers i remember: radius = 10
Force for glider question was 3.5N
work done or whatever it was for that question i got 1.30 cause work done is 1/2fx not fx
mass 119kg
for the further reason why it is better for last question i said about energy supply is constant
2 angle questions i got 11 something and 53 i think
efficiency 27.3% rounded

WHAT WAS THE ROCKETS ABOUT NET FORCE OR NET MOMENT? cause how can you assume that it creates a turning effect
and what did people for the initial KE question, i said that energy was not totally transferred from KE to GPE
Original post by .Username.
and what did people for the initial KE question, i said that energy was not totally transferred from KE to GPE


Only the vertical component of kinetic energy will be converted.

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