Ball a is dropped from rest from a window. at the same instant, ball b is thrown downward; and ball c is thrown upward from the same window. which statement concerning the balls after their release is necessarily true if air resistance is neglected?
(a) at some instant after it is thrown, the acceleration of ball c is zero.
(b) all three balls strike the ground at the same time.
(c) all three balls have the same velocity at any instant.
(d) all three balls have the same acceleration at any instant.
(e) all three balls reach the ground with the same velocity.