Energy is conventionally measured in Calories as well as in joules. One Calorie
ID: 1774991 • Letter: E
Question
Energy is conventionally measured in Calories as well as in joules. One Calorie in nutrition is one kilocalorie, defined as 1 kcal4 186 J. Metabolizing 1 g of fat can release 9.00 kcal. A student decides to try to lose weight by exercising. He plans to run up and down the stairs in a football stadium as fast as he can and as many times as necessary. To evaluate the program, suppose he runs up a flight of 85 steps, each 0.15 m high in 74.0 s For simplicity, gnore the energy he uses in coming down which is small Ass me that a ypical efficiency for human muscles s 20.0% Therefore when your bod converts 100 J from metabolizing fat, 20 J goes into doing mechanical work (here, climbing stairs). The remainder goes into extra internal energy. Assume that the student's mass is 78.0 kg. (a) How many times must the student run the flight of stairs to lose 1.00 kg of fat? times (b) What is his average power output, in watts and horsepower, as he runs up the stairs? hp (c) Is this activity in itself a practical way to lose weight? This answer has not been graded yet. Need Help?Read ItExplanation / Answer
(A) W = 85 x 9.8 x 0.150 = 124.95 J
Energy burn = 124.95 / 0.20 = 624.75 J
Energy required to loose kg fat= (1000)(9)(4186)
= 37.67 x 10^6 J
n = (37.67 x 10^6) / 624.75
n = 60300 times
(B) P = 624.75 / 74 = 8.4 Watt
P = 0.011 hp
(C) No, this is not practical way.
power output is very less.
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