A person running in place on an exercise machine for 10 min uses up 17 kcal (food calories).Another person exercises by repeatedly lifting two 2.5-kg weights a distance of 50 cm.How many repetitions of this exercise are equivalent to 10 minutes of running in place? Assume that the person uses negligible energy in letting down the weights after each lift.(1 cal = 4.186 J)
A)730
B)1450
C)1500
D)2200
E)2900

Question

Quizplus · Accepted Answer

To find the number of repetitions, first convert 17 kcal to joules: 17 kcal * 4186 J/kcal = 71162 J. The work done per lift is mgh = 2 * 2.5 kg * 9.8 m/s² * 0.5 m = 24.5 J. Divide the total energy by the energy per lift: 71162 J / 24.5 J/lift ≈ 2900 lifts.

A Person Running in Place on an Exercise Machine for 10