During a workout, a person repeatedly lifts a 13 lb barbell through a distance of 1.5 ft. How many "reps" of this lift are required to burn off 100 Cal?

Answer 1

This problem is more complicated than it looks, because the body is nowhere near 100% efficient in doing work. The actual work involved each time the barbell is lifted is 13 x 1.5 = 19.5 ft lb.

19.5 ft lb = 6.43 gram-calories = 0.00643 "food" Calories

100 Calories of actual work would be performed after 100/.00643 = 15,550 lifts, but 100 Calories of food energy would be burned long before that

Answer 2

thanks a bunch!