A 4kg ball is on a 5 m ledge. If it is pushed off the ledge, how much kinetic energy will it have just before hitting the ground?

According to law of conservation of energy;

Potential energy at the top = kinetic energy at the bottom

as the ball travels downwards, its potential energy is converted into kinetic energy

Potential energy (PE) = mass (m) * gravitational acceleration (a) * height (h)

where m = 4 kg, a = 9.8 m/s² and h = 5 m

Kinetic energy (KE) = 0.5*mass (m) * velocity (v) ²

where m=4 kg, and v = ?

PE = 4*9.8*5=196 J

since PE = KE

KE=196 J