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)