Calculate the energy in kcal used by a 55 kg woman who does 55 deep knee bends in which her center of mass is lowered and raised 0.400 m. (She does work in both directions.) You may assume her efficiency is 20%.

Energy = 1.132887kcal

Explanation:

Given

Mass = 55kg

Knee bend = 55

Efficiency = 20%

Displacement = 0.4m

First, we'll calculate the total Workdone

Work done = 2n(mgh)

Where n = 55, m = 55kg, g = 9.8m/s² and h = 0.4m

Work done = 2 * 55 * 55 * 9.8 * 0.4

Work done = 23,716J

Since the woman's efficiency is 20% of her total work done;

Then, .her energy = 20% of 23,716J

= 4,743.2

= 4.74KJ

Energy in kcal = 1.132887kcal