[mahmoud khodary]

Electrical Energy = Potential Energy
E.E = P.E
P.E = m *g * h
m = 1 ton = 1000 kg h = 10 m
E.E = P.E = 1000* 9.81 * 10 = 98100 Joule

Joule = Watt second
98100/(1000 * 3600) = 0.027 kw h