Question

A car moving at 27.8 m/s encounters a resistive air frictional force of 215 Newtons. How much power must the engine generate to maintain this speed?

Answer 1

The engin must generate the same force, $F = 215N$ in order to maintain any constant speed. But in ordrer to maintain particulary $v = 27.8m/s$, it mast generate the following power:

$$P = Fv = 215N\cdot 27.8m/s = 5977\space W$$

Answer. 5977 W.