The mass of the car is 1800 kg and the engine power is 36 kW. Friction coefficient 0.1.

The mass of the car is 1800 kg and the engine power is 36 kW. Friction coefficient 0.1. What is the maximum constant speed that a car can travel on a horizontal road?

m = 1800 kg.

g = 10 m / s2.

μ = 0.1.

N = 36 kW = 36000 W.

Vmaх -?

For the movement of a car on an inclined plane, Let us write 2 Newton’s law in vector form: m * a = Fт + m * g + N + Fтр, where Fт is the thrust force of the car engine, m * g is the gravity of the car, N is the reaction force of the road surface , Ftr – friction force.

Since, according to the condition of the problem, the car moves uniformly, then its acceleration is a = 0.

Ft + m * g + N + Ftr.

OH: 0 = Ft – Ftr.

OU: 0 = – m * g + N.

Ft = Ftr.

N = m * g.

The friction force Ffr is expressed by the formula: Ffr = μ * N = μ * m * g.

Fт = μ * m * g.

We express the power of the car N by the formula: N = A / t = Ft * S / t = Ft * Vmax.

Vmax = N / Fт = N / μ * m * g.

Vmax = 36000 W / 0.1 * 1800 kg * 10 m / s2 = 20 m / s.

Answer: the maximum vehicle speed can be Vmax = 20 m / s.