A 66-kg woman cheats on her diet and eats a 590-Calorie (590 kcal) jelly doughnu

Question

A 66-kg woman cheats on her diet and eats a 590-Calorie (590 kcal) jelly doughnut for breakfast.

(a) How many joules of energy are the equivalent of one jelly doughnut?

(b) 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.

(c) If the human body is only 29% efficient in converting chemical energy to mechanical energy, how many stairs must the woman climb to work off her breakfast?

Explanation / Answer

A 66-kg woman cheats on her diet and eats a 590-Calorie (590 kcal) jelly doughnut for breakfast

(a) joules of energy are the equivalent of one jelly doughnut = 590*4184 joule =2468560 joule

(b.) height of a single stair = 15 cm. = 0.15 m

number of stairs = n

acceleration due to gravity = 9.8 m/s2

2468560 joule = 66*g*(0.15n)

n = 25443.8

Hence the woman must climb 25444 stairs .

(c.) Efficiency = 29% = 0.29

2468560*0.29 = 66*g*(0.15n)

n = 7378.71

Number of stairs = 7379

Related Questions

Navigate

• Browse (All)
• Browse A
• Subjects

Integrity-first tutoring: explanations and feedback only — we do not complete graded work. Learn more.