You are Here: Home

# M2 Question help quickish plz watch

1. A red snooker ball that was at rest is hit directly by a white ball moving at 0.8ms-1 after the collision the red ball moves at 0.75ms-1. Find the speed of the white ball after the collision, assuming the momentum is conserved. State clearly any further assumption you have made.
2. are they in a straight line, or is it an oblique impact?
3. It doesnt say, although the first part of the question says:

list four factors that could influence the outcome of a collisions between 2 snooker balls that are rollong along a straight line towards each other.
4. (Original post by imasillynarb)
A red snooker ball that was at rest is hit directly by a white ball moving at 0.8ms-1 after the collision the red ball moves at 0.75ms-1. Find the speed of the white ball after the collision, assuming the momentum is conserved. State clearly any further assumption you have made.
assuming:
1) they are in a straight line
2) their masses are equal
3) it is an elastic collision

0.8 + 0 = v + 0.75

v = 0.05 m/s

A trck A of mass 15 tonnes moves along a straight railway line with a speed of 8ms-1. It colldies with a truck B of mass 10 tonnes which is moving with a speed of 4ms-1 along the same line and in the same direction. During the collision the impulse acting on each truck has magnitude 30000Ns. Calculate the speed of truck A and B immediately after the collision and the total loss of kinetic energy due to the collision.

I got 7 and 10 ms-1 which is clearly wrong as it cant of sped up surely?
6. (Original post by imasillynarb)
I got 7 and 10 ms-1 which is clearly wrong as it cant of sped up surely?
it can speed up. consider a 15 tonne truck hitting a grain of rice. the grain of rice will speed up a lot. it depends on the masses. generally, if a large mass hits a small mass, the small mass will speed up quite a bit, and the large mass will decelerate a small bit.
7. (Original post by elpaw)
it can speed up. consider a 15 tonne truck hitting a grain of rice. the grain of rice will speed up a lot. it depends on the masses. generally, if a large mass hits a small mass, the small mass will speed up quite a bit, and the large mass will decelerate a small bit.
The combined speeds before = 12ms-1 combined speeds after = 17ms-1 ...cant of done that surely?
8. (Original post by imasillynarb)
A red snooker ball that was at rest is hit directly by a white ball moving at 0.8ms-1 after the collision the red ball moves at 0.75ms-1. Find the speed of the white ball after the collision, assuming the momentum is conserved. State clearly any further assumption you have made.
It depends whether there was a "kick" when the balls made contact - i.e.) fricition due to excess deposited chalk.

This would otherwise slow down the speed of the white ball after the collision.
9. (Original post by bono)
It depends whether there was a "kick" when the balls made contact - i.e.) fricition due to excess deposited chalk.

This would otherwise slow down the speed of the white ball after the collision.
Serious help only please, I have to be up in 6 hours.
10. (Original post by imasillynarb)
Serious help only please, I have to be up in 6 hours.
Sorry.
11. (Original post by imasillynarb)
The combined speeds before = 12ms-1 combined speeds after = 17ms-1 ...cant of done that surely?
15*8² + 10*4² = 1120
15*7² + 10*10² = 1240

OK that's impossible from an energy point of view, in the current situation.

but it is generally possible. think about a truck hitting an atom. the truck will carry on with a similar speed, but the atom could go off at a few hundred m/s. the speeds after are much greater than the speeds before. so it is possible.

but in your case, you have made a mistake somewhere, because the energy has increased, which shouldnt be the case.
12. (Original post by elpaw)
assuming:
1) they are in a straight line
2) their masses are equal
3) it is an elastic collision

0.8 + 0 = v + 0.75

v = 0.05 m/s
ms^-1 is more appropriate
13. (Original post by elpaw)
15*8² + 10*4² = 1120
15*7² + 10*10² = 1240

OK that's impossible from an energy point of view, in the current situation.

but it is generally possible. think about a truck hitting an atom. the truck will carry on with a similar speed, but the atom could go off at a few hundred m/s. the speeds after are much greater than the speeds before. so it is possible.

but in your case, you have made a mistake somewhere, because the energy has increased, which shouldnt be the case.
I dont understand where the mistake is, thats my point.
14. (Original post by bono)
ms^-1 is more appropriate
why is it more appropriate?
15. (Original post by elpaw)
why is it more appropriate?
My teacher said so?
16. 5.2 and 7.2ms-1, how does that sound?
17. (Original post by imasillynarb)

A trck A of mass 15 tonnes moves along a straight railway line with a speed of 8ms-1. It colldies with a truck B of mass 10 tonnes which is moving with a speed of 4ms-1 along the same line and in the same direction. During the collision the impulse acting on each truck has magnitude 30000Ns. Calculate the speed of truck A and B immediately after the collision and the total loss of kinetic energy due to the collision.

I got 7 and 10 ms-1 which is clearly wrong as it cant of sped up surely?
15000*8+10000*4 = 160000

15000A + 10000B = 160000 - 30000 = 150000

A = 5.2
B = 7.2
18. (Original post by imasillynarb)
5.2 and 7.2ms-1, how does that sound?
that sounds good, because the energy goes down, so it's OK
19. (Original post by elpaw)
that sounds good, because the energy goes down, so it's OK
I got B = 5.2 and A = 7.2 though, not the other way round :/
20. (Original post by imasillynarb)
I got B = 5.2 and A = 7.2 though, not the other way round :/
oh well, i didnt do the complete solution, i saw your answers and put them in, because they sound right.

TSR Support Team

We have a brilliant team of more than 60 Support Team members looking after discussions on The Student Room, helping to make it a fun, safe and useful place to hang out.

This forum is supported by:
Updated: March 10, 2004
Today on TSR

### Congratulations to Harry and Meghan!

But did you bother to watch?

### What do you actually do at University?

Poll

The Student Room, Get Revising and Marked by Teachers are trading names of The Student Room Group Ltd.

Register Number: 04666380 (England and Wales), VAT No. 806 8067 22 Registered Office: International House, Queens Road, Brighton, BN1 3XE