The resistive force acting against a car’s motion is assumed to vary in proportion to the square of the car’s speed. When the speed is $20\,\text{m s}^{-1}$, the force has a magnitude of $800\,\text{N}$. What effective power must the car’s engine provide in order to keep the car moving at a constant speed of $40\,\text{m s}^{-1}$?
- A$32\,\text{kW}$
- B$64\,\text{kW}$
- C$128\,\text{kW}$
- D$512\,\text{kW}$