(a) How many hours does it take him to work off a 450 Calorie bagel if he stays in bed all day?

Question

(b) How long does it take him if he's working out?
2 h

(c) Calculate the amount of mechanical work necessary to lift a 126 kg barbell 2.10 m.
3 J

(d) He drops the barbell to the floor and lifts it repeatedly. How many times per minute must he repeat this process to do an amount of mechanical work equivalent to his metabolic rate increase of 650 W during exercise?