A car weighing 1 ton, starts off and accelerates to a speed of 72 km / h at a distance of 100 m. Find the engine thrust force.

m = 1 t = 1000 kg.

V0 = 0 m / s.

V = 72 km / h = 20 m / s.

S = 100 m.

Fт -?

When the car accelerates, the force of resistance to its movement will be neglected, that is, we will consider it equal to 0. The car accelerates under the action of the engine thrust force Fт.

2 Newton’s law: Fт = m * a, where m is the mass of the car, a is the acceleration of the car during acceleration.

The acceleration of the car a will be expressed by the formula: a = (V ^ 2 – V0 ^ 2) / 2 * S. Since the car starts its motion from the state of rest V0 = 0 m / s, the formula will take the form: a = V ^ 2/2 * S.

Ft = m * V ^ 2/2 * S.

Ft = 1000 kg * (20 m / s) ^ 2/2 * 100 m = 2000 N.

Answer: during acceleration, the traction force of the car is Ft = 2000 N.