Gravitational potential energy changes into kinetic energy. The equation for gravitational potential energy is GPE = mgh, where m is the mass in kilograms, g is the acceleration due to gravity (9.8 on Earth), and his the height above the ground in meters.
Therefore for the problem:
m = 70 kg
g = 10m/s^2
h = 10m
GPE = mgh = (70kg)(10m/s^2)(10m) = 7000 J or 7 kJ
I hope my answer has come to your help. God bless you and have a nice day ahead!