Answer is: potential energy is 1960 J.
m(medicine ball) = 40 kg.
h = 5 m.
g = 9,8 m/s².
Ep = m·g·h.
Ep = 40 kg · 9,8 m/s² · 5 m.
Ep = 1960 N·m = 1960 J.
Joule is equal to the energy transferred to an object when a force of one newton acts on that object (in this case medicine ball) in the direction of its motion through a distance of one metre.
