Late for his morning workout, a 75kg man eats a 200calorie energy bar for breakf
ID: 1517833 • Letter: L
Question
Late for his morning workout, a 75kg man eats a 200calorie energy bar for breakfast. The energy equivalent of the energy bar is 8.372X10^5 J. On a stair climber exercise machine, each step can be thought of as increasing the gravitational potential energy of the man-earth system. If the equivalent height of each step is 12cm, how many steps must the man take to work off the energy of the energy bar? assuming the efficiency of the human body in converting chemical energy to mechanical energy is 20%. answer is 1.90X10^3 steps... but I am doing something wrong
Explanation / Answer
total energy = 8.372x 10^5
energy converted int mechanical is = 0.2 x total energy
mechanical energy = n (mg x0.12)
0.2 x8.372x10^5 = n (75x9.8x0.12)
n = 1898.41
or
n = 1.9 x 10^3 steps
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