Gravitational Potential Energy (GPE) before fall = Kinetic energy on impact GPE = mgh GPE = 5kg x 9.8m/s^2 x 10m GPE = 490 J Kinetic Energy = 490 J
(This is assuming that gravitation field strength (g) is 9.8m/s^2, sometimes you may round this to 10m/s^2, therefore making the final result: Kinetic energy = 500 J)