A skier, mass 61.00 kg is at the top of a hill and starts down with an initial speed of 3. He does no work on the way down. Assume that the hill...

A skier, mass 61.00 kg is at the top of a hill and starts down with an initial speed of 3.1m/s. He does no work on the way down. Assume that the hill surface is frictionless. Find his speed at the bottom of the hill which is 15m below the top.
A bloc of mass 1 kg moves on a frictionless incline ( none of the forces on the block are shown). It's intial velocity is v_0=2m/s, and it slides a vertical distance h=5m up the slope and its final velocity is v_f=4m/s. Find the external work done on the block.
A baseball outfielder throws a baseball of mass 0.18kg at speed of 39m/s and initial angle of 25 degrees. What is the kinetic energy of the baseball at the highest point of the trajectory? Ignore air friction.