Object above the ground Velocity question?

Question

if an object of mass 20kg starts at 5m above the ground what are the kinetic and potential energies at 2.5m above the ground? what is the objects velocity at this same height

Answer 1

Potential energy in this case always equals mgh, mass x acceleration due to gravity x height above the ground. Kinetic energy is (1/2)m(v^2), which is initially zero since v=0.

At halfway down (2.5 m), half of that potential has been converted to kinetic, so set that amount equal to (1/2)m(v^2) and solve for v to get the velocity at that point.

Answer 2

KE + PE = constant (energy is conserved)

PE = m g h
KE = 1/2 m v^2

Solve the equations and the answer is clear.