Mechanical energy physics question?

Question

A 0.450 kg baseball comes off a bat and goes straight up. At a height of 10.0m, the baseball has a speed of 24.5m/s.

A. Determine its mechanical energy at this height and show work please.

B. What is the baseball's mechanical energy when it is at a height of 9.0m? Explain your answers please.

Answer 1

Mech energy = Potential energy + kinetic energy

A.

PE = mass*gravitational acceleration*height

PE = .45*9.8*10 = 44.1 Joules

KE = 1/2 * mass * velocity^2

KE = 1/2*.45*24.5^2 = 135.1 Joules

ME = KE + PE = 179.2 Joules

B. Mechanical energy is always conserved between potential/kinetic energies in freefall so 179.2 Joules again.