A(n) 0.251 kg soccer ball approaches a player

horizontally with a speed of 15.8 m/s. The
player illegally strikes the ball with her hand
and causes it to move in the opposite direction
with a speed of 27.3 m/s.
What is the magnitude of the impulse delivered
to the ball by the player?
Answer in units of kg m/s.

1 answer

Ft = change in mv, that is mvf-mvi. Be careful on this one. If you choose to make the initial positive you must make the final negative because it's going in the opposite direction. And note you don't need to find F or t, the impulse IS Ft.