Chapter 12, Problem 70A

To determine

The efficiency of the given engine and the waste heat produced by it per second.

Answer to Problem 70A

  $0.34$ , and $3500\text{J}$ , respectively

Explanation of Solution

Given:

The output released by the engine, $\frac{W}{t}=1800\text{J/s}$

The input heat given to the engine, $\frac{Q_H}{t}=5300\text{J/s}$

Formula used:

The efficiency of an engine is given by,

  $\epsilon =\frac{W}{Q_H}$

Where W is the useful work done by the engine, $Q_H$ is the input heat given.

Calculation:

Above formula of efficiency is given by,

  $\epsilon =\frac{\left(\frac{W}{t}\right)}{\left(\frac{Q_H}{t}\right)}$

Using the given values in above,

  $\begin{array}{c}\epsilon =\frac{1800}{5300}\\ =0.34\end{array}$

Now for $1\sec$ , $W=1800\text{J/s}$ and $Q_H=5300\text{J/s}$ .

Then the heat released at waste is,

  $\begin{array}{c}{Q}_L=Q_H-W\\ =5300-1800\\ =3500\text{J}\end{array}$

Conclusion:

The efficiency of the given engine and the waste heat produced by it per second $0.34$ , and $3500\text{J}$ , respectively.