Help please with physics

please help with this question

http://img683.imageshack.us/img683/1170/img0842dg.jpg

regards

First step is to calculate the potential energy of Ball A where it is:

PE = mgz = 3 * 9.8 * 12 = 352.8 J

Now, all of this will be converted to kinetic energy, and all that kinetic energy given to Ball B, where it is. But then Ball B will climb the hill to Point II, and some of that kinetic energy will be converted to potential energy. Let's calculate how much:

PZ = mgz = 2.5 * 9.8 * 8 = 196 J

Subtract that amount from the energy it got from Ball A: 352.8 - 196 = 156.8 J

That will be the kinetic energy remaining to Ball B.

All done!