# Homework Help: 2d Motion Q

1. Feb 17, 2010

### bon

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

A small sphere is released from rest and after falling a vertical distance h freely under gravity, bounces on a smooth inclined plane ( at an angle theta less than 90 degrees to hotizontal ). Given that there is no energy loss on impact, in what direction will it move after impact? Show the dist. down the plane between this impact and the next is 8hsintheta..

2. Relevant equations

Not sure?

3. The attempt at a solution

I guess you choose axis parallel and perp to the plane..but im not sure what to do next..? Confused :S Which equations/physical principles can I use? Do i write equations of motion?

2. Feb 17, 2010

### aim1732

For elastic collisions you know - Angle and velocity of incidence = Angle and velocity of reflection
If you find this angle then resolve acc. due to gravity and use kinematical eqns. for distance.

3. Feb 17, 2010

### bon

So when it says - in what direction will it move directly after impact..is this the same angle wrt the plane as it approaches?

Could you explain in slightly more detail please?

Thanks!

4. Feb 18, 2010

### aim1732

You would have to relate it to the angle of inclination of the plane.
A little effort would show that they are equal.You can then proceed with the kinematic eqns.