Aperson tosses a ball from the ground up into the air at an initial speed of 10 m/sec and an initial angle of 43◦ off the ground. after the ball is released, what is the total acceleration vector acting on the ball when the ball is at the top of its arc? 1. 9.8 m/s2 , down 2. none of these 3. 9.8 m/s2 , up 4. zero 5. 9.8 m/s2 , in the horizontal direction