Two balls with masses of 200 g and 600 g are moving towards

Two balls with masses of 200 g and 600 g are moving towards each other at a speed of 2 m / s, determine the speed of the balls after inelastic interaction.

m1 = 200 g = 0.2 kg.

m2 = 600 g = 0.6 kg.

V1 = 2 m / s.

V2 = 2 m / s.

V “-?

Let’s write the law of conservation of momentum in vector form: m1 * V1 + m2 * V2 = (m1 + m2) * V.

The impact is called inelastic if, after interaction, the bodies move at the same speed, they stick together into a single whole.

Let us draw a horizontal coordinate axis directed towards the motion of the ball with mass m1, find the expression for the law of conservation of momentum for projections onto this axis.

m1 * V1 – m2 * V2 = (m1 + m2) * V “.

V “= (m1 * V1 – m2 * V2) / (m1 + m2).

V “= (0.2 kg * 2 m / s – 0.6 kg * 2 m / s) / (0.2 kg + 0.6 kg) = – 1 m / s.

The sign “-” means that the balls after interaction will move in the opposite direction of the coordinate axis, in the direction of the movement of the second ball.

Answer: the speed of the balls after impact will be V “= 1 m / s.