A car weighing 30 tons, moving at a speed of 10 m / s, collides with a stationary car weighing 20 tons

A car weighing 30 tons, moving at a speed of 10 m / s, collides with a stationary car weighing 20 tons, after which they continue to move together. Determine their speed after exposure.

By the condition of the problem, we have:

m1 = 30 tons = 30,000 kg – the mass of the first car;

v1 = 10 m / s – speed of the first carriage;

m2 = 20 tons = 20,000 kg – the mass of the second car.

It is required to find the speed after collision v2.

According to the law of conservation of momentum (momentum):

m1 * v1 = (m1 + m2) * v2, that is, the product of the speed and the mass of the first car is equal to the product of the sums of the masses of both cars and their speed. Hence:

v2 = m1 * v1 / (m1 + m2) = 30,000 * 10 / (30,000 + 20,000) = 6 m / s.

Answer: the speed of the cars after interaction will be equal to 6 m / s