If a man takes a diet which giveshim energy equal to 9500 kJ per day and he expends energy in all forms to a total of 12000 kJ per day, what is the change in internal energy per day ? If the energy lost was stored as sucrose ( 1632kJper 100 g ) , how many days should it take to lose 1 kg ? Ignore the water loss.

If a man takes a diet which giveshim energy equal to 9500 kJ per day a

1.	If a man takes a diet which giveshim energy equal to 9500 kJ per day and he expends energy in all forms to a total of 12000 kJ per day, what is the change in internal energy per day ? If the energy lost was stored as sucrose ( 1632kJper 100 g ) , how many days should it take to lose 1 kg ? Ignore the water loss.
Answer» Solution :Loss of energy per day `= 12000- 9500 = 2500kJ` Since the man can be considered as a system with constant volume, hence lossof energy can be taken as equal to THELOSS of internal energy. As internal energy decreases, `Delta U` is negative. THUS CHANGE in internal energy. `Delta U = 2500 kJ` For a loss of 1632 kJ of energy , SUCROSE `( C_(12) H_(22) O_(11))` lost `= 100` G ( given ) For a loss of 2500 kJ of energy, sucrose lost` = (100) /( 1632) xx 2500 g = 153.2 g` Thus, 153.2 g of loss of weight takes place in 1 day `:.` 1 kg ( 1000g ) of loss of weight will take place in `(1)/(153.2) xx 1000` days `=6.5 ` days