A cart with a mass of m1 = 20 kg moves in a straight line along a horizontal path with a speed v1 = 2.8 m / s.

A cart with a mass of m1 = 20 kg moves in a straight line along a horizontal path with a speed v1 = 2.8 m / s. At some point, a bag of m2 = 30 kg vertically falls on it. What is the speed of further movement of the cart with the bag on it?

The impulse of a cart without a bag is p1 = m1 * v1, while together with a bag p2 = (m1 + m2) * v2.
According to the law of conservation of momentum: p1 = p2, then:
m1 * v1 = (m1 + m1) * v2
v2 = m1 * v1 / (m1 + m2) = 20 * 2.8 / 50 = 1.12m / s