Power against speed

A car on a level road meets a steady resisting force. You will make the program find the power it needs at every speed, for three resisting forces, and the top speed that a $45\ \text{kW}$ engine can reach.

The idea. At a steady speed the engine's force equals the resistance $F$, so the power is $P = Fv$.

Your tasks.

1. Work out the power, in kilowatts, at every speed, for each force.
2. Find the power for the $700\ \text{N}$ force at $90\ \text{km/h}$.
3. Find the top speed, in km/h, of a car with a $45\ \text{kW}$ engine against $1000\ \text{N}$.