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# Edexcel M3 Exam Discussion watch

• View Poll Results: How hard did you find Edexcel M3?
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6
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8
15
31.25%
7
7
14.58%
6
5
10.42%
5 - Okay
4
8.33%
4
1
2.08%
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1 - Very Easy
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1. I should think boundaries fairly low looking at the poll at the top of the thread and bearing in mind people on this site are probably above average (?)- also the way things are going with Alevel maths becoming easier to pass these days...
2. My answers were as follows:

1.
Dist of CoM from O = 8/3

2.
(a) Prove CoM
(b) k = 2/7

3.
(a) F = 19.7 N
(b) v = 5.44 ms-1

4.
VC = 2a

5.
(a) 1.81 ms-1
(b) Prove equation with sin(a) and tan(a)

6.
(a) Plot graph
(b) Show d=39m
(c) t = 6.98s (5e^(1/3))

7.
(a) v = sqrt(gl/2)
(b) Min length of AB = L/2
3. (Original post by samd)
7. a) v = root(gl/2)
b) 5l/6
I think your answer to 7(b) is correct. Several other people in my school got that as well. Can you explain how you did that please?
4. Does anyone remember question 5 (exactly)?
5. Looking good! Seems as if were all going to do alright!
6. (Original post by ArVi)
I think your answer to 7(b) is correct. Several other people in my school got that as well. Can you explain how you did that please?
Yes I got 5l/6 as well.
7. (Original post by C4>O7)
Does anyone remember question 5 (exactly)?
Two elastic string, both attached to a particle of 2 kg in the middle. AB (end of string) = 1.5m.

a) find speed when it has fallen 1m from rest
b) prove [email protected] + [email protected] = 5
8. such a horrible paper. glad I don't need it as part of my final overall score
9. my answers (not sure which bits of questions they are)...

1. 2.4
2. 45a/112, 1/8
3. pi (oh dear lol), 5.44
4. 2a,
5. 7/rt15, couldn't do the show that
6. 2<t<5, 39, 6.98
7. rt(gl/2), 5l/6

most seem the same as others on the thread which is good. Just quations 2 and 3 and the show that. Thought that show that was horrible anyone want to show me how to do it? Also how did you get k=2/7?
10. (Original post by ArVi)
Two elastic string, both attached to a particle of 2 kg in the middle. AB (end of string) = 1.5m.

a) find speed when it has fallen 1m from rest
b) prove [email protected] + [email protected] = 5
oh god part b had me in a hell of a pickle.

I had something like [email protected] - [email protected] = 0.15

It took me 5 mins to work out I had to multiply through by [email protected]
11. (Original post by ArVi)
Two elastic string, both attached to a particle of 2 kg in the middle. AB (end of string) = 1.5m.

a) find speed when it has fallen 1m from rest
b) prove [email protected] + [email protected] = 5
lambda = 49N
l = 0.75m

when in equilbrium APB = [email protected]
12. (Original post by ssmoose)
my answers (not sure which bits of questions they are)...

1. 2.4
2. 45a/112, 1/8
3. pi (oh dear lol), 5.44
4. 2a,
5. 7/rt15, couldn't do the show that
6. 2<t<5, 39, 6.98
7. rt(gl/2), 5l/6

most seem the same as others on the thread which is good. Just quations 2 and 3 and the show that. Thought that show that was horrible anyone want to show me how to do it? Also how did you get k=2/7?
You were given the centre of mass of the whole object. You knew the centre of mass of the bowl from the previous question. Then you just drew out the table.

Sum of (mass x y) = sum of masses x y-bar
13. (Original post by Widowmaker)
oh god part b had me in a hell of a pickle.

I had something like [email protected] - [email protected] = 0.15

It took me 5 mins to work out I had to multiply through by [email protected]

I know! I left it till the end. I was wondering what was going on cos I had all the correct coefficients but [email protected] all over the place!
14. (Original post by joe_the_smoe)
lambda = 49N
l = 0.75m

when in equilbrium APB = [email protected]
Oops, sorry! forgot that that data was given
15. (Original post by Widowmaker)
Yes I got 5l/6 as well.
Is this the length you got 5l/6 for (pls see attachment)
Attached Images

16. (Original post by Widowmaker)
You were given the centre of mass of the whole object. You knew the centre of mass of the bowl from the previous question. Then you just drew out the table.

Sum of (mass x y) = sum of masses x y-bar
17. You were given the centre of mass of the whole object. You knew the centre of mass of the bowl from the previous question. Then you just drew out the table.

Sum of (mass x y) = sum of masses x y-bar
S***. I did COM of a half sphere and COM of the liquid rather than COM of what i worked out in part a... dur
18. (Original post by ArVi)
Two elastic string, both attached to a particle of 2 kg in the middle. AB (end of string) = 1.5m.

a) find speed when it has fallen 1m from rest
b) prove [email protected] + [email protected] = 5
(Original post by joe_the_smoe)
lambda = 49N
l = 0.75m

when in equilbrium APB = [email protected]
thanks
I worked out the diagonal was 1.25 but then wrote extension =0.25 instead of 0.5
19. (Original post by Widowmaker)
oh god part b had me in a hell of a pickle.

I had something like [email protected] - [email protected] = 0.15

It took me 5 mins to work out I had to multiply through by [email protected]
You think it took you a long time?

I gave up on it and only went back to it after I couldn't do Q7b. Then it hit me, what if I write [email protected] as [email protected]/[email protected], aha!

Can anyone describe how they got 5l/6 for Q7b? I got completely lost there.
20. (Original post by thefish_uk)
You think it took you a long time?

I gave up on it and only went back to it after I couldn't do Q7b. Then it hit me, what if I write [email protected] as [email protected]/[email protected], aha!

Can anyone describe how they got 5l/6 for Q7b? I got completely lost there.

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