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OCR A-Level Physics 2018 UNOFFICIAL MARK SCHEME

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Hi there, for the one thats average force =13.9N can you remind me of the q!! I forgot what if was and am trying to remember if I got that or not. Thank you!

It gave a time in contact and velocity as it hit the ground and it came to rest (I think it was like 25ms)

Reply 21

Invective

What was the reason why the clothes providing weight wasn't an example of Newton's Third law?

Reply 22

flamesofsnow

What did people get for the multiple choice about damping with which statements were correct - was it 2 and 3?

Reply 23

muchunknown

Original post by Invective

What was the reason why the clothes providing weight wasn't an example of Newton's Third law?

Forces acted on same body and of different types I believe!

Reply 24

flamesofsnow

Also for the clothes falling how were you meant to calculate v?

Reply 25

flamesofsnow

What was the answer to the protractor question and the one about no error bars?

Reply 26

Higuys24

Why was the graph -2 gradient

Reply 27

Invective

Original post by flamesofsnow

Also for the clothes falling how were you meant to calculate v?

1/2mv^2 = mgh, rearrange to giving v = (square root)2gh

Reply 28

Higuys24

For the hertzburg Russel diagram. What two stars where they ?

Reply 29

Ihatescales

Original post by Tainer

Was 0.5m the radius or the diameter of the washing machine? I was rushing cuz of the six markers and didn't read it properly :frown:

Hey again lol, remember me from last year? haha. It was the diameter of the machine.

Reply 30

muchunknown

Original post by flamesofsnow

Also for the clothes falling how were you meant to calculate v?

Centripetal force=only weight=mg as no normal reaction force meaning mg=mv²/r therefore v=root(gr)

Reply 31

Ihatescales

Original post by Higuys24

For the hertzburg Russel diagram. What two stars where they ?

I put white dwarf and red giant.

Reply 32

Invective

Original post by Higuys24

For the hertzburg Russel diagram. What two stars where they ?

White Dwarf and Red giant

Reply 33

Ihatescales

Original post by Higuys24

Why was the graph -2 gradient

g = GM/r^2
= log(g) = log(GM) - log(r^2)
= log(g) = log(GM) - 2log(r)
thus log(g) = -2log(r) + log(GM)
y = mx + c

I think this is right?

Reply 34

Invective

Original post by Higuys24

Why was the graph -2 gradient

Wasn't able to finish it but lg(g) = lg(GM) - 2lg(r)

Reply 35

Invective

What did everyone get for the ratio of mass of earth to mass of mars?

Reply 36

Ihatescales

Original post by Invective

What did everyone get for the ratio of mass of earth to mass of mars?

I got 9

Reply 37

Invective

Original post by Ihatescales

I got 9

Do you remember how the process that got you to that answer?

Reply 38

muchunknown

Original post by Invective

What did everyone get for the ratio of mass of earth to mass of mars?

I got 9.88: g=GM/r^2 distance from earth was 4.4*10^10 iirc therefore distance from mars=(5.8-4.4)*10^10. Then just equate the g of each and turns out as 9.88 if I am correct.