[a10]

(Original post by Mr M)
Sorry - I don't know if you will get anything if you did not even set up the model correctly.

for the last part of 7iii) i did everything right except for i put a minus so i had

0.5 x 3.1= -0.5v -1.5v

1.55 = -2v

v= -0.775

I made the mistake of putting the 1.5 as a minus how many marks would i lose for that?

[chroli1]

(Original post by Mr M)
Mr M's OCR (not OCR MEI) M1 Answers May 2012


1. (i) F = 15 N and angle = 61.9 degrees (4 marks)

(ii) E = 17 and angle = 118 degrees (2 marks)


2. (i) v = 3.08 m/s and s = 2.016 m (4 marks)

(ii) 2.669 m (4 marks)


3. (i) 1.6 (2 marks)

(ii) 12.6 m (5 marks)


4. (i) Show coefficient (4 marks)

(ii) 6.02 m/s (6 marks)


5. (i) T = 4.9 N (3 marks)

(ii) 0.49 Ns (5 marks)

(iii) 0.248 m (5 marks)


6. (i) m = 0.500 kg (2 marks)

(ii) H = 10.5 N (2 marks)

(iii) Show coefficient (6 marks)

(iv) Yes (3 marks)


7. (i) 3.1 m/s (3 marks)

(ii) (a) 3.1 (1 mark)

(b) 0.903 m (4 marks)

(c) -1.8 metres per second squared (3 marks)

(iii) 1.415 m/s (4 marks)

How did you do 5ii?

[MrBlueMo0n]

(Original post by chroli1)
How did you do 5ii?

You have to work out the speed that the particle hits the ground, remembering that they both travel at the same speed.

I'm guessing you know how to do momentum, mass x velocity. This worked out to be 0.49kgms^-1, which is the unit that I put, I hope this is accepted because I think it means the same thing as Ns.

So you have your initial momentum, and you have to calculate the momentum after the incident. The question states that it stays on the ground, not moving, so the momentum for the particle now is 0. Therefore the change in momentum is 0.49 - 0 = 0.49 (kgms^-1 or Ns).

I do hope this helps, bearing in mind that this is my first post on TSR

[MrBlueMo0n]

(Original post by a10)
for the last part of 7iii) i did everything right except for i put a minus so i had

0.5 x 3.1= -0.5v -1.5v

1.55 = -2v

v= -0.775

I made the mistake of putting the 1.5 as a minus how many marks would i lose for that?

Yes it should have been -0.5v + 1.5v. I remember making sure it was the right way round and it worked out to be 1v = 1.55

So to answer your question, I think you should only lose one mark, but I am not experienced in this in any way, so don't get your hopes up.

[MrBlueMo0n]

I got the same answers for everything apart from two that you put down with 4 significant figures. I wrote down enough significant figures and then cut it down to 3. Of course, this is what we were supposed to do so I can't have lost any marks at all.

The only thing I can't remember is 7. (ii) (b), but I got (c) and (iii) (correct to 3 significant figures, so 1.42ms^-1) correct so I must have got that right too.

I've never been in this sort of boundary (100%) before so I'm not sure if I just straight off get 100% or I lose loads of method marks and only get 80%. For example, a 5 marks question for every question and I only get 4, that's 80% which is a massive drop. It's pretty scary waiting all summer for this lol. But I'm confident I got an A though (it's 80%) right?

[Tukazoar]

Can someone (Mr M) or anyone else who knows, answer how many marks would be acheived out of four for those who put the answer as 1.55ms-1 to the very last question please.

[Tukazoar]

also, for the prove the co-eff question, how many marks out of 6 do you guys think would be achieved if I used all the right values (weight component, tension component) etc but just mixed up the signs?

[tooambitious]

(Original post by Tukazoar)
also, for the prove the co-eff question, how many marks out of 6 do you guys think would be achieved if I used all the right values (weight component, tension component) etc but just mixed up the signs?

I did this drop 2-3

[chroli1]

(Original post by MrBlueMo0n)
You have to work out the speed that the particle hits the ground, remembering that they both travel at the same speed.

I'm guessing you know how to do momentum, mass x velocity. This worked out to be 0.49kgms^-1, which is the unit that I put, I hope this is accepted because I think it means the same thing as Ns.

So you have your initial momentum, and you have to calculate the momentum after the incident. The question states that it stays on the ground, not moving, so the momentum for the particle now is 0. Therefore the change in momentum is 0.49 - 0 = 0.49 (kgms^-1 or Ns).

I do hope this helps, bearing in mind that this is my first post on TSR

That's fine. I understand. My answer just didn't match because I miscalculated the mass of Q. I instead used the method where you work out the net force acting on it (F=ma) and multiplied by time (0.3) to get change in momentum. The wrong mass obviously gives the wrong answer. How many marks would I lose?

[Kaspersky]

Hi Mr M. Can you tell me how many marks I would drop for stupidly finding the distance B ran as 16m and not 8m, getting my answer to be 4.6m?

[Alex J]

If i got the incorrect answer by mixing up signs in 5(i), how many marks will I lose, bearing in mind this answer is used in subsequent questions too. will i get error carried forward or am I royally screwed?

[MrBlueMo0n]

(Original post by chroli1)
That's fine. I understand. My answer just didn't match because I miscalculated the mass of Q. I instead used the method where you work out the net force acting on it (F=ma) and multiplied by time (0.3) to get change in momentum. The wrong mass obviously gives the wrong answer. How many marks would I lose?

Well it was 5 marks, so lose one for an incorrect answer and 1 for wrong method. That would be 3, but we know this would be a very nice examiner marking it. So maybe you needed to use the right method and then also input the correct values, this would mean that you would probably lose 3 marks, making it 2 out of 5.

Keep up your hopes, I'm on the same level as you so I really don't know any more than you. Maybe I'm talking complete gibberish, and you get 3 out of 5 instead (bearing in mind I can't remember the question exactly and I haven't seen your working).

How did you do for C1 and C2? I presume you are taking maths mechanics and not further maths. Weigh everything up with them and then you can get a better feel for how you've done - it's not just about 1 exam.

[jonnny]

For the questions where you had to prove the coefficient of friction, on the following question where you had to use it, how many marks would I drop for using my (incorrect) coefficient of friction instead of the one given?

I'm such an idiot

This was posted from The Student Room's iPhone/iPad App

[AC94]

I completely screwed up question 6 >___< I hate ring questions.

[MrBlueMo0n]

(Original post by AC94)
I completely screwed up question 6 >___< I hate ring questions.

How did you do with everything else?

[As_Dust_Dances_]

(Original post by MrBlueMo0n)
Yes it should have been -0.5v + 1.5v. I remember making sure it was the right way round and it worked out to be 1v = 1.55

So to answer your question, I think you should only lose one mark, but I am not experienced in this in any way, so don't get your hopes up.

I got v=1.55 for the last question too :/ but wasn't the answer 1.42 or something so how many marks will I lose do you think?

[MrBlueMo0n]

(Original post by As_Dust_Dances_)
I got v=1.55 for the last question too :/ but wasn't the answer 1.42 or something so how many marks will I lose do you think?

Yes, I was just confusing it with something else. I did get 1.42 though, so I can't really remember how you worked out 1.55 (Me confusing it with other questions).

Well, first off, did you get all of the rest of 7 correct? If you messed up one and carried it forward then you won't lose any marks, but this is likely not to be the case.

[As_Dust_Dances_]

(Original post by MrBlueMo0n)
Yes, I was just confusing it with something else. I did get 1.42 though, so I can't really remember how you worked out 1.55 (Me confusing it with other questions).

Well, first off, did you get all of the rest of 7 correct? If you messed up one and carried it forward then you won't lose any marks, but this is likely not to be the case.

Yeah I got the rest of 7 correct based from the answers on here so I'm not sure what I did, I ended up with 1v = 1.55 though

[MrBlueMo0n]

Then surely you only lost 1 mark. Probably a simple addition error

Is that all you got wrong? If so, things look up for you.

[As_Dust_Dances_]

(Original post by MrBlueMo0n)
Then surely you only lost 1 mark. Probably a simple addition error

Is that all you got wrong? If so, things look up for you.

Oh no, I made a few other silly mistakes too like on 4ii where you had to find the initial velocity after the 14n force was removed. I actually got an answer of 0.601 when the answer was 6 but I did it a completely different way..