# Homework Help: Transfer of momentum .help needed ?

1. May 21, 2010

### subho123

transfer of momentum.....help needed ???

1. The problem statement, all variables and given/known data

two particles of masses m1 & m2 are moving along a straight line with velocities u & v respectively. they collide to each other..if the collision between them is an elastic collision then show that momentum transfered from first particle to second particle is 2m1*m2(u - v)/m1 + m2....

2. Relevant equations

I am trying to use the condition of an elastic collision...their linear momentum & kinetic energy will be conserved..but the proof is not coming out....please help me with it.........

if the velocity of first particle after collision is u1 & the same of the 2nd particle is v1 then we know, u1 = (m1 - m2)*u/(m1 + m2) + 2m2*v/(m1 + m2)

v1 = 2m1*u/(m1 + m2) - (m1 - m2)*v/(m1 + m2)

3. The attempt at a solution
1. The problem statement, all variables and given/known data

2. Relevant equations

3. The attempt at a solution

2. May 21, 2010

### ehild

Re: transfer of momentum.....help needed ???

ehild

3. May 22, 2010

### subho123

Re: transfer of momentum.....help needed ???

v1 = 2m1*u/(m1 +m2) - (m1 - m2)*v/(m1+m2)

momentum of the 2nd particle after collision

m2v1 = 2m1*m2*u/(m1+m2) - (m1-m2)*m2*v/(m1+m2)

transfer of momemtum

m2v1 - m2v = 2m1*m2*u/(m1+m2) - (m1-m2)*m2*v/(m1+m2) - m2v

[2m1*m2*u - (m1-m2)*m2*v - (m1+m2)*m2v]/(m1+m2)

[2m1*m2*u - (m1-m2)*m2*v - m1*m2*v - m2^2v]/(m1+m2)

[2m1*m2*u - m1*m2v + m2^2v - m1*m2*v - m2^2v]/(m1+m2)

[2m1*m2*u - 2m1*m2*v]/(m1+m2)

2m1*m2(u-v)/(m1+m2)

it is sloved

BTW thanks

4. May 22, 2010

### ehild

Re: transfer of momentum.....help needed ???

Good job!

ehild