a ball is thrown vertically upward from 12m level in an elevators shaft with an initial velocity of 18 m/sec . At the same instant, an open platform elevator passes the 5m level, moving upward with a...

a ball is thrown vertically upward from 12m level in an elevators shaft with an initial velocity of 18 m/sec . At the same instant, an open platform elevator passes the 5m level, moving upward with a constant of 2m/sec . determine (a) when ball hit the elevator (b) relative velocity of the ball with respect to the elevator when balls hits the elevator