what is vertical impulse required to slow his downward velocity to zero after catching the pass?

Question

an 80 kg basketball player catches a pass in the air after landing immediately jumps to dunk. (vertical velocity is 3 m/s downward) and (vertical velocity is 4 m/s upward)

Answer 1

Impulse is equal to the change in momentum. You know the player's mass and the velocities before and after. From that you can calculate delta momentum. That'll be the impulse.