Chapter 15, Problem 66GP

(a)

To determine

The amount of fat burnt to maintain the desired body temperature.

Answer to Problem 66GP

The amount of fat burnt to maintain the desired body temperature is $0.27\text{kg}$ .

Explanation of Solution

Given info:

The internal energy by the 1 kg of fat is, $U=3\times {10}^7\text{J}$ .

The metabolizing rate of the man is, $P=95\text{W}=95\text{J}/\text{s}$ .

The time for fat to burn is, $t=1\text{day}=1\text{day}\times \frac{86400\text{s}}{1\text{day}}=86400\text{s}$ .

Formula Used:

The expression to calculate the amount of fat burnt to maintain the desired body temperature is,

  $M=\frac{Pt}{U}$

Calculation:

Substitute all the values in the above expression.

  $\begin{array}{c}M=\frac{\left(95\text{J}/\text{s}\right)\left(86400\text{s}\right)}{3\times {10}^7\text{J}}\\ =0.27\text{kg}\end{array}$

Conclusion:

Thus, the amount of fat burnt to maintain the desired body temperature is $0.27\text{kg}$ .

(b)

To determine

The number of days to burn the given mass.

Answer to Problem 66GP

The number of days to burn the mass is 3.7 days.

Explanation of Solution

Given info:

The mass for the burning is, $m=1\text{kg}$ .

Formula Used:

The expression to calculate the number of days to burn the mass is,

  $T=\frac{m}{M}$

Calculation:

Substitute all the values in the above expression.

  $\begin{array}{c}T=\frac{1\text{kg}}{0.27\text{kg}}\\ =3.7\end{array}$

Conclusion:

Thus, the number of days to burn the mass is 3.7 days.