Official OCR A G481 mechanics 20th May 2013

So if you got an A why did you resit?

are you taking A2 ?

Why not?

Nope I'm still in AS

This exam was really tough... it seemed more like an exam of understanding all of the possible exam tricks than physics, like how on the stress/strain graph the strain was given in %...

Why is everyone saying that you had to convert the percentage????? You did not have to convert it as strain doesn't have any units you can convert it to, right?

yes strain has no units but the percentage strain is= (x/L)x 100 so to get the original strain you divide the original by 100... I hope so because that's what I did. because if you think about - the wire would have extended by 80cm if you simply used 0.8m but an extension of 0.008m is more plausible- I hate how I got all the easy marks wrong and I understand these little evil schemes from the examiners

Okay, that makes sense, guessing I will only pick 1 mark out of the possible 3 marks then I think this paper would have been more accessible to those doing maths A-Level as the amount of maths you had to do was overwhelming!

Why not?

It was 41 in Jan and that was easier.

if we are on about the same question, that's what I thought until I heard everyone talking about the force F being the same as something because the raindrop was in equilibrium- seriously fml i'm so sc****d, I just put it's 0 because cos90=0

I put zero too I hope that's right


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I put 0 too, I just remember being taught that if it is perpendicular to the slope then it is zero because it is cos90

I put 0 too, I just remember being taught that if it is perpendicular to the slope then it is zero because it is cos90

You're right in that cos90 does equal zero, however there was a component of the weight acting both parallel and perpendicular to the plane. The component of the weight parallel to the slope was the only force in the same plane as F, and since you know it is in equilibrium, the two forces must be equal.

As for just resolving the components, you are told the plane is at angle of 30 degrees to the horizontal, which means that the component of the weight perpendicular to the slope will be 30 degrees to the right of where it was drawn. You then use cosine to 'close' the angle.

Btw sorry if the diagram is unclear...

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That's a bit low. I must be used to further maths, where its about 61/75 for an A


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that's around the usual 80% mark and the January were only really low because the exam was difficult but personally I think this was a lot harder