You indicated that the acceleration at point D is opposite in direction to the velocity.� When the angle between the velocity and acceleration is 180�, then the ball slows down while moving in a straight line.� When the ball is at point D is it slowing down?� Is it moving in a straight line?

In addition, remember that at point D the ball is flying through a vacuum.� Hence, the acceleration of the ball at point D is the freefall acceleration (i.e., the acceleration of gravity).� In what direction is the freefall acceleration?

Detailed Help Theory