A weightlifter is trying to carry a 10 kg weight held over his head across the room. How much energy will be required to do this work on the 10 kg weight?

Answer 1

No energy will be required, as no work is being done one the weight as it is carried across the room.

Wnc = Fdcos90
cos90 = 0
Wnc = 0
Wnc = change in Emech
change in Emech = 0