# Conservation of kinetic energy/linear momentum problem

1. Nov 3, 2013

### jhahler

1. The problem statement, all variables and given/known data
An 8-kg sphere A is moving to the left with a velocity of 15 m/s when it strikes the 45° inclined surface of a 10-kg block B which is moving to the right a 5 m/s. The ball strikes the block 1 meter above the ground. The block is supported by rollers and impact is perfectly elastic. Determine the speeds of A and B after the impact.

2. Relevant equations
1/2mb(vb)^2 + 1/2ma(va)^2 = 1/2mb(vb)^2 + 1/2ma(va)^2 (initial kin. energy = final kin. energy)
mbvb + mava = mbvb + mava (initial linear mom. = final linear mom.)

3. The attempt at a solution
I know to use those 2 equations to solve for the 2 unknowns Vb final and Va final, but the only thing that's messing me up is what to do with the 45° incline on the block, and I think that the ball striking the block 1 foot about the ground is irrelevant, but I'm not positive. Any help is much appreciated.

2. Nov 4, 2013

### phyneach

Try and resolve the 'v' of the inclined block into its horizontal component. And then put the derived 'v' into the equation.