A weightlifter holding a 500 kg barbell waist high carries the barbell at a constant height and a constant speed to a rack 2 m away, and places the barbell on the rack at the same height at which he was carrying it. How much work does the weightlifter do on the barbell?

Question

A weightlifter holding a 500 kg barbell waist high carries the barbell at a constant height and a constant speed to a rack 2 m away, and places the barbell on the rack at the same height at which he was carrying it.  How much work does the weightlifter do on the barbell?

bobpursley · Answer

Constant height? He did not work against gravity, then.