Assuming 50% efficiency, 150 kcals of chemical energy would result in of kinetic energy.

Efficiency is defined as the measure of the amount of work or energy is conserved in a certain process. At all times, in every process, work or energy is always lost or wasted due to certain interference. Not all work given is converted to useful work or energy. Thus , efficiency is calculated by dividing the energy or work output to the energy or work input then the value is multiplied by 100 to express efficiency as percentage.

Efficiency = (energy output / energy input)

0.50 = kinetic energy produced / 150 kcals chemical energy

kinetic energy produced = 75 kcals

answer: i would say the brain but it seem that you have a brain.