Edexcel - M3 - 18th May 2016

What do people think the 90 ums boundary will be??
also is there anyone whos done fp2 and fp3, how do they compare to m3 (made stupid mistakes in m3 so hoping to get 270+ with m2/fp2 and fp3)

nope

v = 12/(x+3)

m = 0.5

work out F at x = 3

F = ma = mv(dv/dx)

v = 12(x+3)^-1
dv/dx = -12(x+3)^-2

so at x = 3, dx/dx = -12(6)^-2 = 1/3

v = 12(3+3) = 2

m = 1/2

mvdv/dx = 2 * 1/2 * 1/3 = 1/3N

Do you remember what the second bit of the question was? Was there even a second bit?
Do you remember how many marks this bit was for? I might have not done it correctly, can't exactly remember though.

yea me too and i couldn't find a thread for M3 IAL

i remember there's a question about showing that OB<l ? sigh idk how to prove that but i think the answer for part b) is 15l/16?

oh and there's a question about SHM (the water level and ladder one)
i'm so confused about the last part of the question (i think i've calculated 11 hours? idk) i think i've ****ked up my paper

Yup its 15l/16. For part A showing OB<l, i showed that the work done against friction when it moves 1/4l is less than the EPE stored inside the string initially. (i.e. 0.1mgl<0.125mgl), so that the particle P is still moving, but idk if this is the most appropriate method.

The ladder one is so confusing(i mean part b)!! I dun even understand what the hell it is asking, i had to skip that part and do it later. my answer is 9.xx hour. (provided that the question means water level rises from "bottom of ladder" to top and falls back to "bottom of ladder", 9.xx hour would be the time for 1 cycle for this) Sigh.

I think velocity was 12/x+3, making the acceleration -144/(x+3)^3. So Force was -72/(x+3)^3..... when x=3, then magnitude of force was 1/3??.. I think??

Yup its 15l/16. For part A showing OB<l, i showed that the work done against friction when it moves 1/4l is less than the EPE stored inside the string initially. (i.e. 0.1mgl<0.125mgl), so that the particle P is still moving, but idk if this is the most appropriate method.

The ladder one is so confusing(i mean part b)!! I dun even understand what the hell it is asking, i had to skip that part and do it later. my answer is 9.xx hour. (provided that the question means water level rises from "bottom of ladder" to top and falls back to "bottom of ladder", 9.xx hour would be the time for 1 cycle for this) Sigh.

What did you guys get for the last one and the rocket one? I feel like I might have messed up the energy one.

Can somebody tell me what we were supposed to put for 7d? the second SHM??

yes and i spent most of the time understanding the question (sigh but i got it wrong)
i remember some of the answers but most of them are probably wrong, idk i think i really screwed up my paper

horizontal circular motion - prove
SHM - a) prove + b) period (is it 2pi√a/g?)
SHM (ladder) - a) speed(1.54mh-1?) + b) length of time (sigh idk)
vertical circular motion - a) prove + b) distance AC? (i think i got 0.6m)
gravitation - a) prove + b) U=√(2/21)gR
elastic string - a) prove OB<l, b) distance OB (15l/16)
centre of mass - a) prove CoM of cone + b) angle between OA and c) vertical (38.2°) + d) value of k (11/4?)

now that i think about it, the paper was pretty straightforward except for the SHM part b one!!!

(0.5+0.3)x (double dot) = -15.4(x)/1.3

I believe, not 100% confident on the modulus of elasticity

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yes and i spent most of the time understanding the question (sigh but i got it wrong)
i remember some of the answers but most of them are probably wrong, idk i think i really screwed up my paper

horizontal circular motion - prove
SHM - a) prove + b) period (is it 2pi√a/g?)
SHM (ladder) - a) speed(1.54mh-1?) + b) length of time (sigh idk)
vertical circular motion - a) prove + b) distance AC? (i think i got 0.6m)
gravitation - a) prove + b) U=√(2/21)gR
elastic string - a) prove OB<l, b) distance OB (15l/16)
centre of mass - a) prove CoM of cone + b) angle between OA and c) vertical (38.2°) + d) value of k (11/4?)

now that i think about it, the paper was pretty straightforward except for the SHM part b one!!!

(0.5+0.3)x (double dot) = -15.4(x)/1.3

I believe, not 100% confident on the modulus of elasticity

Posted from TSR Mobile

Okay but didn't it seem like a weird question? Only because we did the exact same thing in (a).

very weird. I was doubting myself

I think it was mainly so we got omega to set us up for the last bit

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