Official OCR A G481 mechanics 20th May 2013

i put it was the same as the component of the weight down the slope/parallel to the slope since the raindrop is stationary

i remember some answers but not the actual questions they were answering :P , so ill just post random answers i got



kgm^-2
giga is 1000 times bigger than mega
density = 1.6x10^-? kgm-3 [forgot what it was to the power of]
force constant is the force per unit extension
R=1.4x10^-5 and F=6.3x10^-5 (something close to the) the F is the same because the raindrop is stationary/in equilibrium

3.5ms^-2 for instantaneous acceleration of a trolley i think
I got ratio of B/A as 2.8N
the moments question i got x(50-x)=12x and i think the answer was 0.37m

the question about power:
-power is rate at which work is done
-work done = 5.4x10^?
-output was 390 Watts
-Input was 1228 Watts / 1.3x10^3 Watts

i wrote for one question something about weight being smaller than drag at t=0.05 because the ball was decelerating and then at t=0.25 they were equal/there was zero acceleration

for the Youngs modulus question i got 1.9x10^9 Pa
Apparently the graph of stress/strain would remain the same :L

For the last question i wrote that it was polymeric but forgot to finish my explanation of why it was good for aeroplane tyres (doh!) :L

i basically fluffed my way through the explanations; dont think i did that well tbh :L did anyone get similar answers to me?

What did people say about the forces of graph.

For the first point I said about the drag force being greater than the weight force which means it deaccelerates.

And for the second point I put about the weight and drag forces being equal which makes constant velocity.

anyone say anything like this?

Mty mark scheme posted.

Electronic copies of the paper wont be available for quite some time

did you say the mark scheme has been posted ?

For the perpendicular component you need to use the cos of the angle, so it was 8x10^-5 (if im right) x cos30

For the parallel component you need to use the sin of the angle, so it was 8 x 10 ^-5 x sin30

were lol

Are you sure it was ^ 10 -5 I thought it was ^ 10 5

Are you sure it was ^ 10 -5 I thought it was ^ 10 5

Did anyone else complain about the spring question? The way it said spring a was extended aswell as spring b, instead of compressed for spring A? probably lost a few people marks! did it wrong at first til i used common sense and got 3.5! not too awful of a paper, easy to make silly mistakes, annoyingly i did 100000 cm3 in 1m3 but its 1000000 instead! ah!

i dont think a rain drop would have a force ( weight ) of 1000000N

Both springs can be extended..it's just one was extended more than the other.

but spring a was compressed from 0.5 to 0.3 meters wasnt it? the wording of the question implied it was stretched i reckon! i might be wrong as im crap at reading questions fully anyway, aslong as others got 3.5ms^-2 then im happy!

Mty mark scheme posted.

Electronic copies of the paper wont be available for quite some time

you guys just like torturing yourselves for no reason, just wait till you get your marks stop estimating what you got that would be pointless!