The impulse given to the ball is equal to the change in its momentum:
J = ∆p = (0.50 kg) (5.6 m/s - 0) = 2.8 kg•m/s
This is also equal to the product of the average force and the time interval ∆t :
J = F(ave) ∆t
so that if F(ave) = 200 N, then
∆t = J / F(ave) = (2.8 kg•m/s) / (200 N) = 0.014 s
Answer:
Part a)

Part B)

Explanation:
As we know that when both the forces are acting on the object in same direction then we will have

as we know that

m = 10.6 kg
now we will have


Now two forces are in opposite direction then we have


Part A)
Now we will have from above two equation

Part B)
Similarly for other force we have

72km/hr = 72000m/3600seconds(we convert km/hr to m/s
= 20m/s
Velocity= 20m/s
In 4seconds,distance covered=20x4= 80m
Therefore,an accident occurs because in 4seconds, the car would have moved past 20m