Question

A lifting machine, having an efficiency of 80% uses 2500J of energy in lifting a 10kg load
over a certain height. If the load is now allowed to fall through that height freely, its velocity
at the end of the fall will be (g=10 m/s2)
a) 10 ms
b) 15 ms
c) 20 ms!
d) 25ms!​

Answer 1

I'm not sure but I think the answer is d)