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Official M4 Edexcel Thread – Wednesday 15th June 2016

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Original post by ChuckNorriss


I think that's the right answer
Reply 121
Avatar for Synn
Synn
1
am not happy with the lack of resisted motion question
Unofficial Markscheme - Let me know if you spot any errors!
1)1/root5
2)k=1
3)5root17 256 degrees 48.5m
4)shown then 6
5)shown then when t=pi/12 speed=U and distance travelled when they meet is (U/6)pi+3
6)shown then sin(theta)=5/6 and it is stable as the second derivative equals 48lmg here
Original post by Ewanclementson
Unofficial Markscheme - Let me know if you spot any errors!
1)1/root5
2)k=1
3)5root17 256 degrees 48.5m
4)shown then 6
5)shown then when t=pi/12 speed=U and distance travelled when they meet is (U/6)pi+3
6)shown then sin(theta)=5/6 and it is stable as the second derivative equals 48lmg here


I screwed up the last bit of question 5, other wise I agree with all your answers. I got the distance = (u/6) +1.5, how many marks do you think I will lose?
Original post by oShahpo
I screwed up the last bit of question 5, other wise I agree with all your answers. I got the distance = (u/6) +1.5, how many marks do you think I will lose?


Well you had a pi/6 to be the time and so I reckon there will be marks for if you had used that and used the assumption that the distance between them is the same as at the start so they have travelled the same distance. That should be piU/6 however (which you may have meant). If you used this assumption which I assume you did then you should be credited for it then you'll get one or two for working out that the rate of extension here is -U so that they are moving together at the speed of U then there may be a mark for using speed=distance/time for this and then a final mark for the answer perhaps. Hopefully from this you can work out how many you may have lost, I predict maybe 3 lost but it depends upon if that U/6 is multiplied by pi or not.
Original post by Ewanclementson
Well you had a pi/6 to be the time and so I reckon there will be marks for if you had used that and used the assumption that the distance between them is the same as at the start so they have travelled the same distance. That should be piU/6 however (which you may have meant). If you used this assumption which I assume you did then you should be credited for it then you'll get one or two for working out that the rate of extension here is -U so that they are moving together at the speed of U then there may be a mark for using speed=distance/time for this and then a final mark for the answer perhaps. Hopefully from this you can work out how many you may have lost, I predict maybe 3 lost but it depends upon if that U/6 is multiplied by pi or not.


Yea it's piU/6, and I did find speed to be 2U but I dont think I used it, hopefully I didn't cross it out. How stupid of me though, that bit is at most an M1 question.
What do you guys think? Was it harder than last year's?
Original post by Ewanclementson
Unofficial Markscheme - Let me know if you spot any errors!
1)1/root5
2)k=1
3)5root17 256 degrees 48.5m
4)shown then 6
5)shown then when t=pi/12 speed=U and distance travelled when they meet is (U/6)pi+3
6)shown then sin(theta)=5/6 and it is stable as the second derivative equals 48lmg here


I got (44/3)mlg for the second derivative
Original post by Ewanclementson
Unofficial Markscheme - Let me know if you spot any errors!

6)shown then sin(theta)=5/6 and it is stable as the second derivative equals 48lmg here

I think I got a rational coefficient. Are you sure it was 48?
Original post by Euclidean
Why does it move at speed 2U?

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U-y^=Ucos6t=-u leading to y dot=2U
Unofficial Markscheme - Corrected
1)1/root5
2)k=1
3)5root17 256 degrees 48.5m
4)shown then 6 d=12e^-1
5)shown then when t=pi/12 speed=U and distance travelled when they meet is (U/6)pi+3
6)shown then sin(theta)=5/6 and it is stable as the second derivative equals 44/3lmg here
Original post by Ewanclementson
Unofficial Markscheme - Corrected
1)1/root5
2)k=1
3)5root17 256 degrees 48.5m
4)shown then 6 d=12e^-1
5)shown then when t=pi/12 speed=U and distance travelled when they meet is (U/6)pi+3
6)shown then sin(theta)=5/6 and it is stable as the second derivative equals 44/3lmg here

Yep got all of them. Shud be 100 :smile:
Original post by physicsmaths
Yep got all of them. Shud be 100 :smile:


What do you think the A* boundary will be?
Original post by oShahpo
I screwed up the last bit of question 5, other wise I agree with all your answers. I got the distance = (u/6) +1.5, how many marks do you think I will lose?


-1 or 2 atmost.
to clarify, for question 4, was 6 the value you got for x when t = 0?
Original post by oShahpo
What do you think the A* boundary will be?

Have no clue I havent looked at boundaries for papers tbh. A rough guess wiuld be 70.
Original post by physicsmaths
Yep got all of them. Shud be 100 :smile:


Damn, I think I lost 20 marks, I am not even joking. What grade is that? I feel devastated after this exam.. I should've done past papers but I really didn't have the time.


Posted from TSR Mobile
Original post by Insight314
Damn, I think I lost 20 marks, I am not even joking. What grade is that? I feel devastated after this exam.. I should've done past papers but I really didn't have the time.


Posted from TSR Mobile


Chill dw.
You have more then enough modules for A*A* so it doesnt matter!


Posted from TSR Mobile
Original post by physicsmaths
Chill dw.
You have more then enough modules for A*A* so it doesnt matter!


Posted from TSR Mobile


But Cambridge is gonna look at them if I miss STEP, or my other A-levels. They would probably immediately reject me with a C in a stupid A-level module.

And the timing was worst it could be, STEP II is tomorrow and I can't think about anything else but my failure in M4.


Posted from TSR Mobile
Original post by Insight314
But Cambridge is gonna look at them if I miss STEP, or my other A-levels. They would probably immediately reject me with a C in a stupid A-level module.

And the timing was worst it could be, STEP II is tomorrow and I can't think about anything else but my failure in M4.


Posted from TSR Mobile


Well this exam wasn't really much about intelligence at all, it i's merely standard stuff that you would have learned if you did a few past papers, so don't blame yourself, it's just that you didn't practice enough. Focus on STEP and show them Cambridge dons who's got the skittles!!

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