The car, moving away, after 100 meters reached a speed of 72 km / h. Find the mass of the car

| August 4, 2021 | education

The car, moving away, after 100 meters reached a speed of 72 km / h. Find the mass of the car if the thrust force of its engine is 2kN.

V0 = 0 m / s.

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

S = 100 m.

Ft = 2 kN = 2000 N.

m -?

According to 2 Newton’s law, the mass of a body m can be determined by the ratio of the force Ft, which acts on the body, to the acceleration a, which this force imparts to the body: m = Ft / a.

The acceleration of the car, and we will express it by the formula: a = (V ^ 2 – V0 ^ 2) / 2 * S, where V, V0 are the final and initial velocity of the body, S is the movement of the body.

Since the car starts moving from a state of rest, then its initial speed V0 = 0 m / s, the formula will take the form: a = V ^ 2/2 * S.

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

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

Answer: the car has a mass m = 1000 kg.



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