A car with a mass of m = 20 t moves with an initial speed v0 = 54 km / h. Find the average force F

A car with a mass of m = 20 t moves with an initial speed v0 = 54 km / h. Find the average force F acting on the car if it is known that the car stops during the time: a) t = 1 min 40 s; b) t = 10 s; c) t = 1 s.

m = 20 t = 20,000 kg.

V0 = 54 km / h = 15 m / s.

V = 0 m / s.

tа = 1 min 40 s = 100 s.

tb = 10 s.

tv = 1 s.

Fа -?

Fb -?

Fв -?

According to Newton’s 2 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.

Acceleration a when braking the car is expressed by the formula: a = (V0 – V) / t. Since the car stopped at the end of its movement, then V = 0 m / s, the formula will take the form: a = V0 / t.

The formula for determining the average force F will take the form: F = m * V0 / t.

Fа = m * V0 / tа.

Fa = 20,000 kg * 15 m / s / 100 s = 3000 N.

Fb = m * V0 / tb.

Fb = 20,000 kg * 15 m / s / 10 s = 30,000 N.

Fв = m * V0 / tv.

Fw = 20,000 kg * 15 m / s / 1 s = 300,000 N.

Answer: Fa = 3000 N, Fb = 30,000 N, Fw = 300,000 N.

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