The equation for the gravitational potential energy Ep is:
Ep=m*g*h where m is the mass of the body, g=9.81 m/s² and h is the height of the body.
First we need to find the mass of the body:
m=Ep/(g*h)=24/(9.81*3)=0.82 kg
Now lets see what it's gravitational potential energy would be on the height of 1 m.
Ep=0.82*9.81*1 = 8 J
On the height of 1 m the body has a gravitational potential energy of Ep=8 J.
