A car with a mass of 20 tons moves at a speed of 3 m / s and is coupled with a stationary car

| February 4, 2021 | education

A car with a mass of 20 tons moves at a speed of 3 m / s and is coupled with a stationary car with a mass of 40 tons. At what speed will this coupler move?

Given:

m1 = 20 tons = 20,000 kilograms – the mass of a moving car;

v1 = 3 m / s (meters per second) – the speed of the carriage;

m2 = 40 tons = 40,000 kilograms – the mass of a stationary car.

It is required to determine v (m / s) – the speed of movement of the system of cars after coupling.

According to the condition of the problem, the second car is stationary, that is, its speed is v2 = 0 m / s. Then, assuming that the adhesion of the cars occurred as a result of an absolutely inelastic interaction, according to the law of conservation of momentum (momentum), we find:

m1 * v1 + m2 * v2 = (m1 + m2) * v, or, given that v2 = 0:

m1 * v1 = (m1 + m2) * v;

v = m1 * v1 / (m1 + m2) = 20,000 * 3 / (20,000 + 40,000) = 60,000 / 60,000 = 6/6 = 1 m / s.

Answer: the speed of the cars after coupling will be equal to 1 m / s.



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