Assuming that all the energy goes into useful work, find how much energy per hour is needed for a 735 W heat engine?

These tasks: N (power of the heat engine taken) = 735 W; t (duration of work) = 1 hour (in SI t = 3600 s).

Since all the energy is spent on useful work, the required amount of energy for 1 hour of work can be calculated by the formula: A = Q = N * t.

Calculation: Q = 735 * 3600 = 2 646 000 J (2646 kJ).

Answer: For 1 hour of operation, a heat engine needs 2646 Joules of energy.