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OCR MEI AS Mathematics M1 10/06/2013 Watch

1. (Original post by johndoe4)
Wait... i got like 1.44s on the last question

views on that?
The quadratic retrieved two values 1.34 and 7.67 me thinks
2. Abi can die in a hole.
3. (Original post by johndoe4)
i got 7/0.4= 17.5
wasnt it like (0, something, 17.5)
4. (Original post by Axion)
The quadratic retrieved two values 1.34 and 7.67 me thinks
what if you usedf v=u+at is that wrong? to get 3.5s
5. (Original post by Axion)
The quadratic retrieved two values 1.34 and 7.67 me thinks
1.34 or 1.44 cant remember....but it could only be one time so you use the -b+the root

7.67 seems a little long tho

i think
6. (Original post by Axion)
wasnt it like (0, something, 17.5)
i got (0,0,17.5)
7. (Original post by JG1027)
what if you usedf v=u+at is that wrong? to get 3.5s
Except you don't know v? I think that's where u may have slipped. We do know s though

(btw i got it wrong so maybe lost 2-3 marks :P)
8. Last Question:
Only force acting down was gravity, where a = -gsin15
The inital velocity is 8 and the inital displacement is 13.
Hence v = -gtsin15 + 8
And s = -0.5gt²sin15 + 8t + 13
Set s = 0 to get t = -1.34025 or t = 7.64833
As t must be positive, the time is 7.65 seconds.
9. (Original post by johndoe4)
1.34 or 1.44 cant remember....but it could only be one time so you use the -b+the root

7.67 seems a little long tho

i think
was the sledge being pushed up or down the slope?
10. (Original post by Axion)
Except you don't know v? I think that's where u may have slipped. We do know s though

(btw i got it wrong so maybe lost 2-3 marks :P)
thing is isnt v=0 as it goes down the slope so it must come to rest?
11. (Original post by Axion)
wasnt it like (0, something, 17.5)
How did you answer that vector equation?
I think I did r-p-q-weight=ma
Weight being vector (0,-4,0) :/
12. (Original post by Axion)
wasnt it like (0, something, 17.5)
What direction did you put.

i added all the forces and got (0,0,7) so magnitude = 7newtons=ma
13. (Original post by JG1027)
i did that but i used v=u+at to find the time would that be wrong? because v=0 u=8 a=2.5 and t=? so rearrange and i got -3.2s so 3.2 s
well firstly the accelaration and velocity would be in different directions so at least one must be negative...
and also that equation wouldnt work out how long it took to the bottom it would work outhow long it would take to reach v=0 at the top of the slope not at the bottom of the slope...
14. (Original post by ayloedxa)
Last Question:
Only force acting down was gravity, where a = gsin15
The inital velocity is 8 and the inital displacement is 13.
Hence v = gtsin15 + 8
And s = 0.5gt²sin15 + 8t + 13
Set s = 0 to get t = -1.34025 or t = 7.64833
As t must be positive, the time is 7.65 seconds.
NONONO there was definitely a negative in the quadratic somewhere
15. (Original post by Jojo_555)
How did you answer that vector equation?
I think I did r-p-q-weight=ma
Weight being vector (0,4,0) :/
yeah weight was defo that vector.

aff em all together and divide by 0.4
16. (Original post by Axion)
yeah weight was defo that vector.

aff em all together and divide by 0.4

Why is weight not (0,0,4)?

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17. first we addd all the forces to get the resultant. as vectors have direction and mag you just add. then =ma
18. (Original post by johndoe4)
first we addd all the forces to get the resultant. as vectors have direction and mag you just add. then =ma
Yeah but mg in this case is 0.4x(0,0,10), no?

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19. (Original post by Axion)
yeah weight was defo that vector.

aff em all together and divide by 0.4
I don't get why they are added together....I thought cuz r had the biggest magnitude, you take them all away from r. I think I've screwed that question up aswell T.T
20. (Original post by stefanocattaneo)
Why is weight not (0,0,4)?

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True. Am not sure tbh. I normally always take it in the j direction but could be wrong

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