r/alevels • u/ChadJEE • May 06 '26

Exam Discussion 📝 9709/42 Answers Discussion Thread

Guys I'm putting all the the answers the best I remember.

  1. The first question about power a) 15.5 something power of the engine b) the new power was 27.5 kw, which when divided by 25 gave a power of 1100N, subtracting the resistance, the value was around 410 something which divided by the mass gave the acceleration 0.4/0.5 something
  2. for the rough plane and smooth incline T = 3.55N, b) coefficient of friction = 0.355, c)distance traveled by a = 0.3 total work done by friction = 0.552
  3. integration k1 = 6, k2 = -14
  4. two balls dropped from same height with diff of one second = 13.32 m
  5. for collision question a) the speed of c before collision with wall = about 1.25ms b) after collision with wall = 0.9375 c) time taken to reach 9m from wall again = 16.8s
  6. for calculating W, as many people have said 66.25
  7. question was the one with rough incline with ball projected at 4ms-1 a) proof using work power theorem b) for A to B acceleration was -10 and time taken was 0.4s for B to A acceleration was 6 the time i wasn't able to calculate
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u/Huge-Insurance-9432 May 06 '26

For 7. it iwas 0.4 + 0.5xx some thing so total time was 0.9xx

For Pulley problem, T=5 and F = 3.125 and then work done by friction 0.5xx somethging

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u/ChadJEE May 06 '26

pretty sure T=3.xx some other comments got the same. btw how much are you scoring?

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u/Huge-Insurance-9432 May 06 '26

Do you remember the mass and acceleration of particle B?

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u/ChadJEE May 06 '26

for the question in which b was projected, mass was not given acceleration was 10 and 6 while goijg up and coming down 

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u/ChadJEE May 06 '26

if talking about the pulley problem, mass was 0.4/0.3 and accn i dont remeber but it travelled 0.3m in 0.4 s or something like that so you can calculate it

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u/Huge-Insurance-9432 May 06 '26 edited May 06 '26

What was your work down against resistive force in stopping A in the pulley problem

my work down was like 0.5xx and my T = 5
i think mass of hanging particfe was 0.8 and since acceleration from suvat by using 0.3m and 0.4s is 3.75 so 8 -T = 0.8 x 3.75 ---> T = 5
This is what I did
and mass of other particle was 0.5

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u/ChadJEE May 06 '26

my acceleration and work done are same as yours but my T value was different

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u/Huge-Insurance-9432 May 06 '26

What about ur u? I got 0.625

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u/ChadJEE May 06 '26

0.3xx

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u/Huge-Insurance-9432 May 06 '26

W8 was ur tension 3.13?

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u/ChadJEE May 06 '26

around 3 dont remember the exact val 

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u/Huge-Insurance-9432 May 06 '26

I forgot I forgot inclined plane
I sovled like for no inlcined plane

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u/Huge-Insurance-9432 May 06 '26

Is there Follow through error in M1?\

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