How can I solve this?

Question

A ball falls from height of 19.5 m, hits the floor, and rebounds vertically upward to height of 15.0 m. Assume that m _ball = 0.215 kg.

(a)What is the impulse (in kg · m/s) delivered to the ball by the floor?

magnitude _____kg · m/s

direction _____

(b)If the ball is in contact with the floor for 0.0300 seconds, what is the average force (in N) the floor exerts on the ball?

magnitude _____N

direction _____

Answer 1

Since the ball goes up directly, the direction for both (a) and (b) should both be vertically upward.

(a), dropping to the ground, the ball has the velocity of v**2=2*g*h1, v1=(2*10*19.5)**0.5=19.49

bouncing back, the ball has the velocity of v**2=2*g*h, v2=(2*10*15)**0.5=17.32

the impulse p=m(v1+v2)= 0.215*(19.49+17.32)=7.9 kg m/s

(b) force f=p/t= 7.9/0.03=263 kg m/s**2 =263 N