calculate kinetic energy

[mikefitz]

http://img445.imageshack.us/img445/4941/untitlediy4.png

This question leaves me very confused. I'm hoping someone can give me an idea of where to begin because we haven't gone over these problems in class. I understand that kinetic energy is energy that a body has as a result of motion, and is defined as one half the product of a body's mass and the square of it's speed.

But how do I express this as an equation given the attached problem? :confused:

Thanks!

[neutrino]

epsilon is the coefficient of restitution. Hint: Start with the ratio K_f/K_i, where K is the kinetic energy.

[dmoravec]

well... very simpily, what does v equal in terms of kinetic energy? try plugging that in the top and the bottom and see what you get.