Consider the image above. vi = the initial velocity and vf = the final velocity. is there acceleration? explain your answer.

a)
no. the initial and final velocities are the same.

b)
yes. the ball had to slow down in order to change direction.

c)
no. acceleration is the change in velocity. the ball's velocity is constant.

d)
yes. even though the initial and final velocities are the same, there is a change in direction for the ball.