#5 part 2 A 66-kg woman cheats on her diet and eats a 710-Calorie (710 kcal) jel

Question

#5 part 2

A 66-kg woman cheats on her diet and eats a 710-Calorie (710 kcal) jelly doughnut for breakfast. How many joules of energy are the equivalent of one jelly doughnut? How many stairs must the woman climb to perform an amount of mechanical work equivalent to the food energy in one jelly doughnut? Assume the height of a single stair is 15 cm. stairs If the human body is only 22% efficient in converting chemical energy to mechanical energy, how many stairs must the woman climb to work off her breakfast? stairs

Explanation / Answer

We know that 1 kcal = 4184 J mass = 58 kg a) 1 jelly implies 449 x 4184 J = 1878.616 kJ b) E = m g h h = E / m g = 1878616 / 58 x 9.8 = 3305.095m Therefore she can climb the stairs n = 3305.095 / 0.15 = 22033.97 c) h = 0.29 x 1878616 / 58 x 9.8 = 958.48m So number of stairs = 958.48/0.15 =6389.87

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