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# M1 OCR (Not MEI) Exam - 9/06/2015 watch

1. (Original post by dsfshello)
How did you get 7ms for 6ivb , surely differentiate to get -6t^2 sub in three to get a velocity of -54, do all the momentum stuff you get 68m-54m=mv divide by ms and your left with 14 ms
That's the right concept and method.
However when they coalesce their mass is 2m, therefore the equation is 68m-54m=2mv
2. Are the answers to force question (question 5) definitely:

5i) 1.04 [3]5ii) 1.06 [3]5iii) a=0 [3]5iv) a=0 [2] ?

These were the answers I got too but there is some debate whether it was push/pull, did it matter? if not can someone explain why it doesn't.

Thanks!
3. What would 50/72 be as a grade and UMS mark?

Also, would I get method marks if I've done the correct method but with the wrong values??
4. Any thoughts on what would happen if I mixed the angles in Q4, i.e. put 54 for A and 35 for B
5. I did a push force instead of a pull force for the question where the angle changed. How many marks do you think I'm likely to lose?
6. (Original post by LukeBarnett)
Are the answers to force question (question 5) definitely:5i) 1.04 [3]5ii) 1.06 [3]5iii) a=0 [3]5iv) a=0 [2] ?These were the answers I got too but there is some debate whether it was push/pull, did it matter? if not can someone explain why it doesn't.Thanks!
(Original post by ms8061)
lot of confusion about whether the forces in 5 were pushing or pulling, look at this:

Attachment 423191

the question stated the angle was above the horizontal, if you take it as pushing down on the block (which would give a negative vertical component) you would be wrong - the angle it makes is below the horizontal.

so it doesn't matter whether or not it's pushing or pulling, just that the angle is above the horizontal. If your force looked like either A, you should be right.

(i think)
as long as your angle is above the horizontal it should be fine
7. (Original post by ms8061)
as long as your angle is above the horizontal it should be fine
So acceleration is defo 0 and not negative if my diagram looked like A. Also will I lose all 5 marks for not getting 0?
8. (Original post by ms8061)
as long as your angle is above the horizontal it should be fine
Surely you got different values for a if the force was pushing rather than pulling as R would be greater
9. (Original post by kaziz)
That's the right concept and method.
However when they coalesce their mass is 2m, therefore the equation is 68m-54m=2mv
How many marks would I lose if I had 68m-54m=mv?
10. Sugar! I got no marks on question 4 at all and maybe like, 3 on question 5. But apart from 1iii I am certain I got absolutely everything else right.

With 1iii I ended up with a quadratic(!) which I used the Eqn feature on my calculator to solve instantly and ended up with an answer of 0.6 exactly.
11. I also liked in Question 7 that half the plane was rough and half was smooth because they did that in June 2014 and I prepared for it, because I know it was poorly answered last year and they would therefore do the same again this year.
12. (Original post by Minecraft27)
Sugar! I got no marks on question 4 at all and maybe like, 3 on question 5. But apart from 1iii I am certain I got absolutely everything else right.

With 1iii I ended up with a quadratic(!) which I used the Eqn feature on my calculator to solve instantly and ended up with an answer of 0.6 exactly.
I got a quadratic too. I solved it, ended up with 0.5 something, and 5. something. So I chose to reject the 0.5 something and state the answer was 5. something. But looks like i should have rejected the other one and stated 0.5something
13. (Original post by ChoccyPhilly)
Surely you got different values for a if the force was pushing rather than pulling as R would be greater
That's exactly what I thought, it seems to me that the resultant calculated from the different ways produces different values?
What would 50/72 be as a grade and UMS mark?

Also, would I get method marks if I've done the correct method but with the wrong values??
almost certainly a B i think

depends on the question, probably 1 on a 2-4 mark, maybe 2 on a 5 marker? shot in the dark really
15. (Original post by benq)
How many marks would I lose if I had 68m-54m=mv?
Probably an a1 and an m1 ?
16. (Original post by alexann95)
I got a quadratic too. I solved it, ended up with 0.5 something, and 5. something. So I chose to reject the 0.5 something and state the answer was 5. something. But looks like i should have rejected the other one and stated 0.5something
I ended up with 0.8-something and -3-something. I rejected -3-something and used the 0.8-something. Then I worked out time to fall 30m, which was 1.4-something. Took 0.8-something off that which gave me exactly 0.6. Though maybe if I didn't round I would have good the 0,598 that everyone else got.

Hopefully I'll still get 2 marks for getting 0.6. I dunno though, I might have got 0.6 by fluke with totally wrong method so they might not allow it at all. In which case, low B here I come!
17. (Original post by LukeBarnett)
That's exactly what I thought, it seems to me that the resultant calculated from the different ways produces different values?
Exactly, so both cannot be right. I has to be one or the other
18. (Original post by ChoccyPhilly)
Exactly, so both cannot be right. I has to be one or the other
The trouble is the question said "force applied" which doesn't indicate push/pull, so it's a question of which one is right I suppose.
19. (Original post by Jamie1997)
You can do either, it makes no difference
(Original post by ms8061)
as long as the angle was above the horizontal, it does not matter
There was a difference. If the force was pushing, downwards then R force would be greater and if the force was pulling upwards then R would be less. Both would result in different values for a

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