Physics problem (momentum)

Question

A 0.58 kg softball has a velocity of 13 m/s at an angle of 29° below the horizontal just before making contact with the bat. What is the magnitude of the change in momentum of the ball while it is in contact with the bat if the ball leaves the bat with a velocity of 25 m/s, horizontally back toward the pitcher?

How would you work this out?

Answer 1

1) draw a picture of the ball before impact showing the direction of motion the determine the components of the ball's velocity. Let down be negative and right be positive.

2) draw a picture of the ball after impact showing the direction of motion the determine the components of the ball's velocity. Check the signs of the vector components. The direction of motion changed!

3) compute the components of the ball's momentum before and after.

4) compute the changes in momentum in both the right-left and the up down directions.

5) use the components of the changes in px and py to find the net change in momentum.

Since the ball was moving down and then horizontal there is an upward change in momentum.

Since the ball changed its horizontal direction of motion the change in momentum in the horizontal direction after the impulse is in the same direction as the final horizontal direction.