What force must be applied to a body with a mass of 12 kg, moving at a speed of 30 km / h, to make it move at a speed of 60 km / h?

m = 12 kg.

V0 = 30 km / h = 8.3 m / s.

V = 60 km / h = 16.6 m / s.

F / t -?

According to 2 Newton’s law, the force F, which acts on a body, is equal to the product of the body’s mass m by its acceleration a: F = m * a.

With uniformly accelerated motion, the acceleration of the body, a shows how quickly the speed of the body changes and is determined by the formula: a = (V – V0) / t, where V, V0 are the final and initial speed of movement, t is the time the speed changes.

F / t = m * (V – V0).

F / t = 12 kg * (16.6 m / s – 8.3 m / s) = 99.6 N / s.

The ratio of force to the time of its action must be F / t = 99.6 N / s.

If the force F = 99.6 N, then it must act t = 1 s.

If the force F = 149.4 N, then it should act for t = 1.5 s.

If the force F = 199.2 N, then it should act t = 2 s.

Answer: F / t = 99.6 N / s.