An engineer connects an electric generator to a stationary bicycle. To lose weig

Question

An engineer connects an electric generator to a stationary bicycle. To lose weight, he rides the bicycle and uses the electrical output to power a 100 W television. The bicycle efficency is 95% and the electric generator efficency is 50%. Every day, he rides the bicycle for 20 minutes. While on this exercise program, he does not increase his daily food intake. In one year, approximately how many kilograms of body fat would be burned off?

Fat has a metabolic energy of 9 kcal/g whereas carbohydrates and protein have a metabolic energy content of 4 kcal/g

Explanation / Answer

television = 100 watt

thus in 1 year energy = 100*365*60*60 J

output of generator = 100*365*60*60 J = 131400000 J

output of bycicle = (100/50)*131400000 =262800000 J

input to bicycle = (100/95)*262800000= 276631578.9473684211 J

thus input = 276631578.9473684211 J = 0.239005736 *276631578.9473684211 cal

= 66116534.1271578947cal= 66116.53412715789 kcal

thus weight lost = 66116.53412715789/9 = 7346.281569684 g

thus weight lost = 7.34628 kg answer

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