W hp To evaluate the program, suppose she runs up a flight of 70 steps, each 0.1
ID: 2141461 • Letter: W
Question
W hp To evaluate the program, suppose she runs up a flight of 70 steps, each 0.150 m high, in 62.5 s. For simplicity, ignore the energy she uses in coming down (which is small). Assume that a typical efficiency for human muscles is 20.0%. This means that when your body converts 100 J from metabolizing fat, 20 J goes into doing mechanical work (here, climbing stairs). The remainder goes into internal energy. Assume the student's mass is 63.0 kg. (a) How many times must she run the flight of stairs to lose 1 pound of fat?Explanation / Answer
calorific value of fat = 9cal/gram
energy released by 1 lbm fat = 453.59*9 *4.182 J
= 17072 J
work output = 0.20 *
work done in climbing n stair = 63*9.8*0.150*n
63*9.8*0.150*n = 0.20*1896.92
n = 36 step
power output
work done = change in potential energy
= mgh
= 63*9.8*(0.150*70)
= 6482.7
power = 6482.7/62.5
= 103.72 W
= 0.139 hp
Related Questions
Navigate
Integrity-first tutoring: explanations and feedback only — we do not complete graded work. Learn more.