I need to find the kinetic energy of a 30 kg child after rolling down a 4 meter incline on roller skates. There is no friction between the incline and the skates.

Question

jamesj · Answer

Since the system is frictionless, all of that gravitational potential energy is converted into kinetic energy.  

So find the potential energy at the top of the ramp and that must be equal to the kinetic energy at the bottom.

anonymous · Answer

great, thanks a lot.

anonymous · Answer

and potential energy is PE=$$PE=mgh$$?

jamesj · Answer

Yes.