A man takes a diet-equivalent to 10000 kJ per day and does work

thermodynamics
cbse

#1

A man takes a diet-equivalent to 10000 kJ per day and does work, in expending his energy in all forms equivalent to 12500 kJ per day. What is change in internal energy per day? If the energy lost was stored as sucrose (1632 kj per 100 g), how many days should it take to lose 2 kg of his weight? (Ignore water loss)


#2

Energy taken by a man = 10000 kj
Change in internal energy per day = 12500 —10000 = 2500 kj The energy is lost by the man as he expands more energy than he takes Now 100 g of sugar corresponds to energy =1632 kj loss in energy
2000g of sugar corresponds to energy = 1632 x 2000 / 100 = 32640 kJ
Number of days required to lose 2000g of weight or 32640 kJ of energy = 32640 / 2500 = 13 days.