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# Edexcel M3 Exam Discussion watch

• View Poll Results: How hard did you find Edexcel M3?
10 - Very Hard
10
20.83%
9
6
12.50%
8
15
31.25%
7
7
14.58%
6
5
10.42%
5 - Okay
4
8.33%
4
1
2.08%
3
0
0%
2
0
0%
1 - Very Easy
0
0%

1. How did everyone find the M3 exam? I thought it was a bit harder than the recent past papers. Anyways, rate how hard (10 - very hard, 1 - very easy, 5 - okay) you thought it was, and we'll try and put together a list of answers for it.

I have got the above answers from posts later on in this thread. They are not necessarily the correct answer

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: [email protected] + [email protected] = 5

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 = 5l/6
2. Holy **** this was so hard... all the other papers I had done were so easy!!!!!!

This make me cry.
3. Last part of last question i couldn't get...

Then the easy Q2 I couldn't get either. I got the masses to be in ratio 2:-1

Then some other question i couldn't do... etc
4. There were a couple of tricky ones towards the end. Overall, the exam was probably harder than the vast majority of past papers.
5. Some of it was rather tricky. And question 6 particularly seemed like lots of labour with very little mechanics.

I also got stuck on 5 b) for a while but cracked it eventually.
6. Question 5 was the only one i got really stuck on,

i kept calculating that it didnt fall enough
7. Arvi: Are we free to discuss the paper yet?
8. i think we shud lol

what did you get for the cone quesiton? how high was it?

what did you get for the last question? "when does p reach origin again?"

what did you get for the the speed of the falling partical attatched to 2 strings?
9. Didnae like it at all. Number 1, my answer had an 8 in it I think. Number 2 I think k was 2/7. Erm, the one with integration was hard. For the last part I think the answer was 6.something but I did that in the last minute.

Some answer was 2a I think (height of something above something).
10. yeah would be grateful if someone could go through solution to partical attatched to 2 strings questions
11. (Original post by tony_)
yeah would be grateful if someone could go through solution to partical attatched to 2 strings questions
a) or b) (this is Q5 for reference) ?

a) Was the speed of it 1 m below I think.

b) This was prove that [email protected] + [email protected] = 5.
12. i did the speed below. i think that was 4.19. but i duno about the other question i couldnt do it... if someone could post up answers to the lot that'd be amazing
13. Answers I remember. Not all of my answers will be i) right ii) remembered correctly.

1. 8/3 (5 marks).

2. a) Proof. (5 marks).
b) k = 2/7 (5 marks).

3. a) 19.7 N
b) 5.44 m/s

4. I got (4root7)a/8. Probably wrong. (11 marks). Widowmaker says 2a. Sounds likely.
5. a) 1.8073... m/s
b) Proof.

6. a) Graph.
b) 2 < t < 5.
c) Proof.
d) t = 6.98 s (probably wrong).

7. a) v = root(gl/2)
b) 5l/6
14. (Original post by samd)
a) or b) (this is Q5 for reference) ?

a) Was the speed of it 1 m below I think.

b) This was prove that [email protected] + [email protected] = 5.
yeah 5a was the bit where i got confused, every time i tried it ended up not reaching 1m below

1. 8/3

2. K= 2/7

3. a)19.7 b) 5.44

4. 2a

5. 1.81

6. b) 2.5<a<5 (this is wrong it should be 2<a<5 very annoyed )

c) 6.98

7. a) sqrt(gl/2) b) (3/4)l - this is probably wrong I spent about 2 mins on it.
16. (Original post by samd)
Answers I remember. Not all of my answers will be i) right ii) remembered correctly.

1. 8/3 (5 marks).

2. a) Proof. (5 marks).
b) k = 2/7 (5 marks).

3. a) 19.7 N
b) 5.44 m/s

4. I got (4root7)/8. Probably wrong. (11 marks).

5. a) 1.8073... m/s
b) Proof.

6. a) Graph.
b) 2 < t < 5.
c) Proof.
d) t = 6.98 s (probably wrong).

7. a) v = root(al/2)
b) 5l/6
I'm always impressed by how well people remember their answers.

Mine were similarish to these.

Definitely got the same for the last question, but got '2a' for Q4, I think.
Couldn't do (6) d), didn't quite undersatnd the Q and didn't have time to spend on it.

For the trig. identitiy type thing, I got a promising looking equation (it had a cot and a cos and a 1/5) but couldn't rearrange it to get the required one. Mind you, I didn't try for long because I was short on time.
17. t = 6.98 is definetly right because I proved it by using my graphical calc to integrate 75t^-1 between 6.98 and 5 and it gives x = 25, and at t = 5, x = -25, so 25 - 25 = 0.
18. (Original post by samd)
Answers I remember. Not all of my answers will be i) right ii) remembered correctly.

1. 8/3 (5 marks).

2. a) Proof. (5 marks).
b) k = 2/7 (5 marks).

3. a) 19.7 N
b) 5.44 m/s

4. I got (4root7)a/8. Probably wrong. (11 marks). Widowmaker says 2a. Sounds likely.
5. a) 1.8073... m/s
b) Proof.

6. a) Graph.
b) 2 < t < 5.
c) Proof.
d) t = 6.98 s (probably wrong).

7. a) v = root(gl/2)
b) 5l/6

I can't remember question 5 at all but I agree with all those answers (2a for Q4.) except for 7b) (I think I got l/2 )
19. I have worked out what I did wrong for Q4. I took the height to be the diagonal!! May have lost like 7 marks for that. Oops!

Anyway apart from that it all looks right. Which is promising.

20. The only one I had problems with was that daft trigonometry one where it hangs in equilbrium with the 2 strings, something like prove 5tanx = 5 + sinx.

Spent 4 whole pages in the book on it, tried using work/energy and forces in equilbrium. Think I ended up with something like tanx = 1+ 5sinx, wasn't happy with this question, only worth 5/6 marks however.

The integral one with the graph kept catching me out, but on the third attempt I realised it asked for the distance travelled, not displacement, and so I did it in two parts and subtracted the minus value from the bit under the graph to make it positive.

The last part of question 7 I didn't do to well. I really didn't know where to start so I just tried using work/energy to set GPE to initial KE, but I got an answer after about 3 lines of working, not good for a 9 mark question. Was really tired at this point and couldn't be bothered starting again.

Overall pretty happy with the paper, providing that 2a is right for q4. Someone else at my school disagreed with it and he virtually gets every question right on every exam. Probably looking at about 85 ums ! (hopefully)!!!

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Updated: June 24, 2006
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