Question

Engine 1 has an efficiency of 0.13 and requires 7200 J of input heat to perform a certain amount of work. Engine 2 has an efficiency of 0.28 and performs the same amount of work. How much input heat does the second engine require?

Answer 1

Answer:

3,342.86J

Explanation:

Engine 1

Quantity of Input Heat, $Q_{H}$  = 7200J

Efficiency,  η = 0.13

                           Efficiency,  η $=\frac{W}{Q_{H}}$

                           ⇒ W = η$Q_{H}$

                                W = 0.13 × 7200

                                W = 936J  

Engine 2

Efficiency,  η = 0.28

Since Engine 2 performs same amount of work as Engine 1, then,

                 Work-done by Engine 2 = Work-done by Engine 1

                                       W₂ = W₁ = 936J

                 Efficiency,  η $=\frac{W}{Q_{H}}$

                 $Q_{H}$ = W / η

                  $Q_{H}=\frac{936}{0.28}$

                  $Q_{H}$ = 3,342.86J

The input heat require by  the second engine is 3,342.86J