After turning off the engine, a car with a mass of 1800 kg travels in free rolling a path equal to 545

| June 15, 2021 | education

After turning off the engine, a car with a mass of 1800 kg travels in free rolling a path equal to 545 m for 80 s before a complete stop. Determine the initial speed, acceleration and force acting on the vehicle during braking.

m = 1800 kg.

S = 545 m.

t = 80 s.

V = 0 m / s.

V0 -?

a -?

F -?

The path traveled by the body S and the acceleration a with uniformly accelerated braking are expressed by the formulas: S = (V0 ^ 2 – V ^ 2) / 2 * a, a = (V0 – V) / t.

Since at the end of braking the car stopped V = 0 m / s, the formulas will take the form: S = V0 ^ 2/2 * a, a = V0 / t.

S = V0 ^ 2/2 * a = t * V0 ^ 2/2 * V0 = V0 * t / 2.

V0 = 2 * S / t.

V0 = 2 * 545 m / 80 s = 13.625 m / s.

a = 13.625 m / s / 80 s = 0.17 m / s2.

The braking force F is expressed by the formula: F = m * a.

F = 1800 kg * 0.17 m / s2 = 306 N.

Answer: V0 = 13.625 m / s, a = 0.17 m / s2, F = 306 N.



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