Question

3. Two identical balls of mass 1.8 kg hit head on and rebounded from each other. One ball was traveling at 9.2 m/s and the other ball at 8.7 m/s in the opposite direction. After collision, the second ball rebounded at a speed of 9.1 m/s. What is the speed of the first ball?

Answer 1

8.7 m/s.

Step-by-step explanation:

The speed of the first ball after the collision can be found using the conservation of momentum. The principle of conservation of momentum states that the total momentum of a closed system remains constant if no external forces act upon it.

Initially, the momentum of the first ball is 1.8 kg * 9.2 m/s = 16.56 kgm/s, and the momentum of the second ball is 1.8 kg * -8.7 m/s = -15.66 kgm/s. The total initial momentum is 0.9 kg*m/s

After the collision, the momentum of the second ball is 1.8 kg * 9.1 m/s = 16.38 kg*m/s.

Since the total momentum must remain constant, the momentum of the first ball after the collision is equal to the total initial momentum minus the final momentum of the second ball.

0.9 kgm/s = 16.56 kgm/s + final momentum of the first ball

final momentum of the first ball = 16.56 kgm/s - 0.9 kgm/s = 15.66 kg*m/s

To find the speed of the first ball after the collision, we can divide its final momentum by its mass:

15.66 kg*m/s / 1.8 kg = 8.7 m/s

So the speed of the first ball after the collision is 8.7 m/s.