A car engine at a speed of 72 km / h consumes 8 kg of diesel fuel for every 100 kilometers. Determine the net power

A car engine at a speed of 72 km / h consumes 8 kg of diesel fuel for every 100 kilometers. Determine the net power of the vehicle engine if the engine efficiency is 40%. Specific heat of combustion of fuel = 44 * 10 to the 6th power J / kg.

Let’s calculate the time it takes for a car to cover a distance of 100 km:

100: 72 = 100/72 hours = 100 * 3600/72 = 5000 s.

Let’s find the energy contained in 8 liters of fuel:

44 * 10 ^ 6 * 8 = 352 * 10 ^ 6 J.

Useful work will be:

A = 353 * 10 ^ 6 * 40/100 = 141 * 10 ^ 6 J.

To determine the power, we use the formula:

P = A / t, where A is work, t is time.

P = 141 * 10 ^ 6/5000 = 28.2 * 10 ^ 3 W = 28.2 kW.

Answer: The car engine power is 28.2 kW.