Heat and physical activity. In a bench press, a weight lifter lifts 113 k g 45 c
ID: 2252053 • Letter: H
Question
Heat and physical activity. In a bench press, a weight lifter lifts 113kg 45cm . In so doing, the athlete expends 1.2 kJ
What's the heat flow involved in this process? kJ
What's the heat flow involved in this process?
How many repetitions does the weight lifter need to make in order to "burn" 120kcal ?
Explanation / Answer
workdone = m*g*h = 113*9.8*0.45 = 498.33 J = 0.498 kJ
a) heat flow = 1.2 k J - 0.498 kJ = 0.702 kJ
b)Q = n*0.702 KJ
120*4.18* k J = n * 702*kJ
n = 120*4.18/0.702
= 715 times