Question

A gasoline engine with a thermal efficiency of 28% has a power out put of 50hp . How much heat must be supplied per second to the engine

Answer 1

By definition, the efficiency is given as follows:

$$\eta = \dfrac{P_{out}}{P_{in}}\times 100\%$$

where $P_{out} = 50hp$ is the output power of the engine, and $P_{in }$ is the heat supplied per second to the engine. Thus, obtain:

$$P_{in} = \dfrac{P_{out}}{\eta}\times 100\% = \dfrac{50hp}{28\%}\times 100\% \approx 179hp$$

Answer. 179 hp.