D Question 1 8 pts A ball was thrown straight upward from an initial height of 3 m, reached a maximum height of 30 m, and then fell to the ground. When the ball was at height 20 m and still traveling upward, the acceleration of the ball was a1. When the ball was at height 20 m and traveling downward, the acceleration of the ball was a2. Which one of the following is correct? O a2 = -a1 O a2 =-2a1 O a2 = 21 O a2 = a1