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# AQA Mechanics 1B 24 May 2012 Unofficial Markscheme Tweet

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1. Re: AQA Mechanics 1B 24 May 2012 Unofficial Markscheme
Hey,
On the projectiles question i proved that sintheta = 0.875 but then followed through into all of my equations with sin0.875. Will i lose all the marks to b,c,d and e or will i pick up follow through marks. Hope i at least get some.
2. Re: AQA Mechanics 1B 24 May 2012 Unofficial Markscheme
(Original post by 1platinum)
I still don't get 7(c)...
When anything is travelling south-east, then the components of i and j must be the same size (the triangle). So, if east is positive i, south is negative j, then you set i = -j, (where i and j are taken from the v = u + at equation), then you rearrange and solve for t. When you find t=20, you sub. that into the v formula, to get the vector for v, which equalled (i -j)m/s. Then convert that to speed using pythag. = root2, = 1.41 (3SF)
Last edited by Oromis263; 24-05-2012 at 16:40.
3. Re: AQA Mechanics 1B 24 May 2012 Unofficial Markscheme
Also got 23.5 for 6c, think I got it all right apart from one assumption, my teachers said it was really hard to get though. Hoping for over 95 ums although I'm thinking extremely high grade boundaries.
4. Re: AQA Mechanics 1B 24 May 2012 Unofficial Markscheme
(Original post by Oromis263)
When anything is travelling south-east, then the components of i and j must be the same size (the triangle). So, if east is positive i, south is negative j, then you set i = -j, (where i and j are taken from the v = u + at equation), then you rearrange and solve for t. When you find t=20, you sub. that into the v formula, to get the vector for v, which equalled (i -j)m/s. Then convert that to speed using pythag. = root2, = 1.41 (3SF)
I'm sure I got t=40.
5. Re: AQA Mechanics 1B 24 May 2012 Unofficial Markscheme
Im getting most of the general answers here, sure I got 23.5 at one point on that question but crossed it out, however I used same method to get another answer so im hoping ill get method marks also never got the 6 mark vector one but I got the first half of it from what I can gather so I should also get method marks there.

Not many other places that I can see that I would have lost marks. Deffinatley should have gotten a mid-high B if not a low-mid A on that paper.
6. Re: AQA Mechanics 1B 24 May 2012 Unofficial Markscheme
(Original post by 1platinum)
I'm sure I got t=40.
I may well be remembering incorrectly, but I think a fair few people I know got 1.41 as the speed, but we'll have to wait until August to find out now! D:
Last edited by Oromis263; 24-05-2012 at 16:39.
7. Re: AQA Mechanics 1B 24 May 2012 Unofficial Markscheme
(Original post by Oromis263)
I may well be remembering incorrectly, but I think a fair few people I know got 1.41 as the speed, but we'll have to wait until August to find out now! D:
Some people got that whilst others got 5.83! Just want someone to confirm the correct answer.
8. Re: AQA Mechanics 1B 24 May 2012 Unofficial Markscheme
(Original post by Oromis263)
I may well be remembering incorrectly, but I think a fair few people I know got 1.41 as the speed, but we'll have to wait until August to find out now! D:
I also got speed =1.41 and that t=30.

Checking your official solution list i do believe my only mistake is a sign one at the start of the tension question (q5) which was pretty stupid but hopefully with ECF that will only be 1-2 marks gone. Not sure about my second modelling assumption either though, i ended up going for the block is modelled as a particle but idk it felt pretty lame.

How difficult do people think the paper was? I think on the whole it might have been marginally harder than the average past paper as there didn't seem to be quite such an abundance of "throw away" questions that you usually get.
9. Re: AQA Mechanics 1B 24 May 2012 Unofficial Markscheme
This paper wasn't particuarly difficult but it was no easier than many past papers and it was harder than some, especially in recent years.
Predicted Boundaries:
72/75 - 100 UMS
58/75- A
52/75-B
47/75-C
42/75-D
37/75-E

Dunno what everyone else thinks
10. Re: AQA Mechanics 1B 24 May 2012 Unofficial Markscheme
(Original post by In One Ear)
I also got speed =1.41 and that t=30.

Checking your official solution list i do believe my only mistake is a sign one at the start of the tension question (q5) which was pretty stupid but hopefully with ECF that will only be 1-2 marks gone. Not sure about my second modelling assumption either though, i ended up going for the block is modelled as a particle but idk it felt pretty lame.

How difficult do people think the paper was? I think on the whole it might have been marginally harder than the average past paper as there didn't seem to be quite such an abundance of "throw away" questions that you usually get.
That's exactly what I went for (in combination with no air resistance), and I felt so torn about it. Changed it between that and g = 9.8 several times, but finally went with the particle one, as g is given on the front of the paper... I don't know, I think a lot of people will have a lot of different answers, so they'll probably have a whole variety of options.

In terms of difficulty, I'm unsure. It had only one or two "Show that.." questions, in which usually you can feel confident with what you're getting, whilst in this one you had to follow through with your calculations and have faith in them! Perhaps around the level of January's paper (73/75 for 100UMS), but maybe not as high as last June's (75/75 for 100UMS)
Last edited by Oromis263; 24-05-2012 at 16:49.
11. Re: AQA Mechanics 1B 24 May 2012 Unofficial Markscheme
jjjj
12. Re: AQA Mechanics 1B 24 May 2012 Unofficial Markscheme
(Original post by Oromis263)
When anything is travelling south-east, then the components of i and j must be the same size (the triangle). So, if east is positive i, south is negative j, then you set i = -j, (where i and j are taken from the v = u + at equation), then you rearrange and solve for t. When you find t=20, you sub. that into the v formula, to get the vector for v, which equalled (i -j)m/s. Then convert that to speed using pythag. = root2, = 1.41 (3SF)
On this I got t=20 but then never made i=-j and did something else (cant remember what I did exactly) but then I did use pythag with my values to get an answer. Do you think Ill get a couple of marks?
13. Re: AQA Mechanics 1B 24 May 2012 Unofficial Markscheme
bump
14. Re: AQA Mechanics 1B 24 May 2012 Unofficial Markscheme
(Original post by Oromis263)
No, as you were finding the time taken for it to come to rest, ie v=0.

0-20 / -2 = 10s
gotta lose marks somewhere
15. Re: AQA Mechanics 1B 24 May 2012 Unofficial Markscheme
(Original post by Oromis263)
That's exactly what I went for (in combination with no air resistance), and I felt so torn about it. Changed it between that and g = 9.8 several times, but finally went with the particle one, as g is given on the front of the paper... I don't know, I think a lot of people will have a lot of different answers, so they'll probably have a whole variety of options.

In terms of difficulty, I'm unsure. It had only one or two "Show that.." questions, in which usually you can feel confident with what you're getting, whilst in this one you had to follow through with your calculations and have faith in them! Perhaps not as low as January's paper (68/75 for 100UMS), but maybe not as high as last June's (75/75 for 100UMS)
It was actually 73/75 for 100UMS on this year's Jan paper..
16. Re: AQA Mechanics 1B 24 May 2012 Unofficial Markscheme
(Original post by mathsguy)
This paper wasn't particuarly difficult but it was no easier than many past papers and it was harder than some, especially in recent years.
Predicted Boundaries:
72/75 - 100 UMS
58/75- A
52/75-B
47/75-C
42/75-D
37/75-E

Dunno what everyone else thinks
Agree that even though I found it an easy paper it was more difficult than some in recent times. I would go:

74/75 100 UMS
62/75 A
54/75 B
49/75 C
43/75 D
17. Re: AQA Mechanics 1B 24 May 2012 Unofficial Markscheme
(Original post by MSI_10)
It was actually 73/75 for 100UMS on this year's Jan paper..
So it was, perhaps I was thinking of Core 4, or something. Thanks
18. Re: AQA Mechanics 1B 24 May 2012 Unofficial Markscheme
You know for getting negative signs for the resistive forces but the correct answers otherwise; how many marks do you think they would penalise you. 1 mark on each, or just 1 for both?
19. Re: AQA Mechanics 1B 24 May 2012 Unofficial Markscheme
7C) Our A level maths God/Assistant just did this question. She got 1.41, it appears the T=40 answer people seem to be getting comes from using r=ut+0.5at^2 to work out the time instead of using V=u+at.
20. Re: AQA Mechanics 1B 24 May 2012 Unofficial Markscheme
(Original post by 1platinum)
You know for getting negative signs for the resistive forces but the correct answers otherwise; how many marks do you think they would penalise you. 1 mark on each, or just 1 for both?
They was two different parts of a question right? They mark each one individually so you will lose 1 mark on each for accuracy. But the method will certainly be right.

For all we know the exam may say "condone negative answer" im not sure. But my answer wasnt negative
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