A ball is fallen freely from top of tower of height 100 m and another ball is thrown upwards with 50 m/s at the same time when they will cross each other ? (g = 10 m//s^(2))

A ball is fallen freely from top of tower of height 100 m and another

1.	A ball is fallen freely from top of tower of height 100 m and another ball is thrown upwards with 50 m/s at the same time when they will cross each other ? (g = 10 m//s^(2))
Answer» 1 s 2 s 3 s 4 s Solution :For the ball falling freely `v _(0) = 0, d = 100 m` `therefore` DISTANCE covered in .t. time `d _(1) = v _(0)t + 1/2 g t^(2)` `d _(1) = 0 + 1/2 (10) t ^(2) = 5t ^(2) ""…(1)` Initial velocity of the ball thrown upwards is `v _(0).=50m//s` and it meets the first ball at `(100 -d _(1)`)m distance `therefore 100 -d _(1) = v _(0) .t = 1/2 g t ^(2)` `therefore 100 - d _(1) = 50 t - 1/2 (10) t ^(2) ` `therefore 100 -d _(1) = 50 t -5t ^(2)` From equation (1), `therefore 100-5t ^(2) = 59 t - 5t ^(2)` `therefore 50 t = 100` `therefore t = (100)/(50)` `therefore t =2s`