# Particle physics -ALEVELS..past paper

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#1
https://pmt.physicsandmathstutor.com...%20A-level.pdf
Q 17 b) and c)
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2 years ago
#2
By conservation of momentum, sum of momenta before = sum of momenta after

so momentum of initial moving particle = sum of momenta of 2 particles after collision

draw a triangle to show this, all vectors should point head to tail (similar to here) Watch this (1:34) for a clear diagram

for part b) resolve and show that the angle between the 2 particles must be 90 degrees

consider conservation of kinetic energy
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#3
(Original post by BobbJo)
By conservation of momentum, sum of momenta before = sum of momenta after

so momentum of initial moving particle = sum of momenta of 2 particles after collision

draw a triangle to show this, all vectors should point head to tail (similar to here) Watch this (1:34) for a clear diagram

for part b) resolve and show that the angle between the 2 particles must be 90 degrees

consider conservation of kinetic energy
this is the link for its marking points
https://pmt.physicsandmathstutor.com...%20A-level.pdf
and in the drawing part they say the angle should be 90 degress
why???
0
2 years ago
#4
(Original post by MARYAM1234567)
this is the link for its marking points
https://pmt.physicsandmathstutor.com...%20A-level.pdf
and in the drawing part they say the angle should be 90 degress
why???
You are given a hint in (c). The angle between the 2 particles after collision is 90 degrees. This is because the collision is elastic
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#5
oh okay no wait i rewatched the video...i get it
thanks alott!!
0
2 years ago
#6
(Original post by MARYAM1234567)
this is the link for its marking points
https://pmt.physicsandmathstutor.com...%20A-level.pdf
and in the drawing part they say the angle should be 90 degress
why???
(Original post by BobbJo)
You are given a hint in (c). The angle between the 2 particles after collision is 90 degrees. This is because the collision is elastic
(Original post by MARYAM1234567)
oh okay no wait i rewatched the video...i get it
thanks alott!!

There is a subtle and important point for the angle between the subsequent paths of both particles must be 90° which is mentioned by the MS implicitly.

In order for the angle between the subsequent paths of both particles must be 90°, the following conditions need to be satisfied:

(1) elastic collision (as mentioned by BobbJo)

(2) the particles involved in the collision must have equal mass (shown in the video post by BobbJo)

If the two particles involved in the elastic collision are of different masses, the angle between the subsequent paths of both particles can be 90° but NOT a must. In fact, the angle can be any value depends on the initial conditions of the problem.
1
#7
(Original post by Eimmanuel)
There is a subtle and important point for the angle between the subsequent paths of both particles must be 90° which is mentioned by the MS implicitly.

In order for the angle between the subsequent paths of both particles must be 90°, the following conditions need to be satisfied:

(1) elastic collision (as mentioned by BobbJo)

(2) the particles involved in the collision must have equal mass (shown in the video post by BobbJo)

If the two particles involved in the elastic collision are of different masses, the angle between the subsequent paths of both particles can be 90° but NOT a must. In fact, the angle can be any value depends on the initial conditions of the problem.
so the main thing is that they should have the SAME MASS and elastic collision for the angle to be 90
thank you soooo much!
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#8
can you also help me in this question..
its not related to the forum but..
https://pmt.physicsandmathstutor.com...%20A-level.pdf
Q12 part b)
0
2 years ago
#9
(Original post by MARYAM1234567)
can you also help me in this question..
its not related to the forum but..
https://pmt.physicsandmathstutor.com...%20A-level.pdf
Q12 part b)

µ is the absolute value of the gradient of the graph.
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#10
(Original post by Eimmanuel)
µ is the absolute value of the gradient of the graph.
shouldnt the gradient be Ro x (the constant)??
0
2 years ago
#11
(Original post by MARYAM1234567)
shouldnt the gradient be Ro x (the constant)??
Note that you are given

R = R0eµl

Take natural log on both sides, we have

ln R = ln R0μl

ln R = ‒μl + ln R0

Compare this with

y = mx + c
0
2 years ago
#12
(Original post by MARYAM1234567)
can you also help me in this question..
its not related to the forum but..
https://pmt.physicsandmathstutor.com...%20A-level.pdf
Q12 part b)
0
#13
(Original post by Eimmanuel)
i was a little in a hurry...but yes i can do that
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