When the car is moving evenly at a speed of 54 km / h, its engine produces 45 kW.

When the car is moving evenly at a speed of 54 km / h, its engine produces 45 kW. What is the force of resistance to movement in this case?

v = 54 kilometers per hour – the speed at which the car is moving;

N = 45 kW – the power developed by the car.

It is required to determine F (Newton) – the force of air resistance.

Let’s translate the units of measurement of speed and power in the SI system:

v = 54 km / h = 54 * 10/36 = 15 meters per second.

N = 45 kW = 45 * 1000 = 45000 watts.

Then the thrust force developed by the engine will be equal to:

Fthrust = N / v = 45000/15 = 3000 Newtons.

Since, according to the condition of the problem, the car moves uniformly, then according to Newton’s first law we get:

Fthrust – F = 0;

F = Fthrust = 3000 Newtons.

Answer: the force of resistance to motion is 3000 Newtons.