#5 PLEASE ANSWER ALL PARTS AND SHOW WORK ! THANKS!!!! A 48-kg woman cheats on he
ID: 1487643 • Letter: #
Question
#5
PLEASE ANSWER ALL PARTS AND SHOW WORK ! THANKS!!!!
A 48-kg woman cheats on her diet and eats a 740-Calorie (740 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. If the human body is only 26% efficient in converting chemical energy to mechanical energy, how many stairs must the woman climb to work off her breakfast?Explanation / Answer
a. 1 calorie= 4.186 J
740 calorie= 740 x 4.186= 3097.64 J
answer is 3097.64 J
b. work done in climbing a stair = mgh = 48 x 9.8 x 0.15 = 70.55 j
no of stairs she needs to climb= 3097.64 /70.55= 43.9 or say 44 stairs
c. mechanical enrgy available= 26% x 3097.64= 805.38 J
no of stairs she needs to climb = 805.38 /70.55= 11.41 or say 12 stairs
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