Answer:
Momentum = 21.44 N.s
Step-by-step explanation:
First we need to find the speed of the ball by using following equation. Assuming the speed of ball to be constant:

where,
v = speed of ball = ?
s = distance covered by ball = 18.3 m
t = time taken = 3.5 s
Therefore,

Now, the momentum of ball will be:

Momentum = 21.44 N.s