Question

When you drink cold water, your body must expend metabolic energy in order to maintain normal body temperature (37° C) by warming up the water in your stomach. Could drinking ice water, then, substitute for exercise as a way to "burn calories?" Suppose you expend 390 kilocalories during a brisk hour-long walk. How many liters of ice water (0° C) would you have to drink in order to use up 390 kilocalories of metabolic energy? For comparison, the stomach can hold about 1 liter.

Answer 1

The number of liters of ice water is 11 L

Step-by-step explanation:

Given data:

normal body temperature = 37°C

temperature of the ice water = 0°C

Cwater = specific heat of water = 4186 J/kg °C

Suppose the person drinks 1 L of cold water, then, the mass is 1 kg

The heat is:

`Q_(water) =mC_(water) (T_(ice) -T_(body) )=1*4186*(0-37)=-154882J`

The sign (-) indicates the energy lost by the metabolic process. If the Qwalk is 390 kilocalories, then the number of liters of ice water is equal to:

`n=(Q_(walk) )/(Q_(water) ) =(390*4186)/(154882) =10.54=11L`