Noninertial frame projectile. A device shoots a small ball horizontally with speed 0.206 m/s from height h = 0.773 m above an elevator floor. The ball lands at distanced from the base of the device directly below the ejection point. The vertical acceleration of the elevator can be controlled. What is the elevator's acceleration magnitude a if d is (a) 14.0 cm, (b) 20.0 cm, and (c) 7.50 cm