A ball with a mass of 100 g, flying at a speed of v1 = 15 m / s, is thrown by a blow of the racket in the opposite

A ball with a mass of 100 g, flying at a speed of v1 = 15 m / s, is thrown by a blow of the racket in the opposite direction at a speed of v2 = 20 m / s. How and by how much has the impulse of the ball changed?

m = 100 g = 0.1 kg.

v1 = 15 m / s.

v2 = 20 m / s.

Δp -?

The momentum of the ball p is a vector physical quantity equal to the product of the mass of the ball and the speed of its movement: p = m * v. The momentum of the ball p is directed in the same way as the speed of its movement v.

Let us write down the change in the impulse of the ball Δp according to the formula: Δp = p2 – p1 = m * v2 – m * v1.

Let’s direct the coordinate axis along the initial movement of the ball. Since when the ball bounces, it will bounce in the opposite direction, then Δp = – m * v2 – m * v1.

Δp = – 0.1 kg * 20 m / s – 0.1 kg * 15 m / s = – 3.5 kg * m / s.

The “-” sign means that the impulse of the ball after rebounding is directed in the opposite direction of the initial movement.

Answer: the momentum of the ball will change by Δp = 3.5 kg * m / s.