A bowling ball is thrown into the alley, having velocity of 3 ms^-1 at the start of the bowling alley. It decelerates at a constant rate, before hitting the skittles at 2 ms^-1 after 4 s A) calculate the acceleration of the ball.

A)  acceleration (m/s2) = change in velocity (m/s) / time (s) 
A) -1.0 ms^-1 / 4 s = -0.25 ms^-2
B) Calculate the displacement the ball travelled before hitting the skittles and hence calculate the average velocity of the ball
d = 1/2 ( Vf + Vi ) × t = 0.5 x (3 + 2) ms ^-1 x 4 s = 10 m
Average velocity = distance / time = 10 m / 4 s = 2.5 m s^-1
C) Finally, as the bowling ball weighs 10 kg, calculate the momentum with which it hits the skittles.
 momentum (kgm/s) = mass (kg) x velocity (m/s) = 10 kg x 2 ms^-1 = 20 kg ms^-1