a very broad elevator is going up vertically with a constant acceleration of 2m/s^2 .At the instant when its velocity is 4m/s a ball is projected from the floor of the lift with a speed of 4m/s relative to the floor at an elevation of 30° The time taken by the ball to return to the floor
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1 Answers
62There is no change of velocity in the horizontal direction.
The acceleration of the ball with respect to the board is 9+2=11m/s2
vertical component of the speed is 4 sin 30 = 2 m/s
final relative displacement = 0
s=ut+1/2 a t2
0 = 2t-1/2. 11. t2
2t = 1/2. 11. t2
t=0 or t=4/11 seconds.
t=0 referes to the initial time..
hence 4/11 seconds.