Question

37. A ball is dropped from top of a tower 250 m high.
At the same time, another ball is thrown upwards
with a velocity of 50 ms from the ground. The
time at which they cross each other is
(1) 3 second
(2) 5 second
(3) 10 second (4) 12 second​

Answer 1

Answer:

(2) 5 second

Explanation:

Let the time when they cross each other be 't' .

Now , For the ball thrown upwards:

Sg = ut - (1/2)gt²

Sg = 50t - 5t² ....(1)

For the ball dropped from tower :

St = ut +(1/2)gt²

St = 5t² ....(2)

Now , St + Sg = 250

Adding (1) & (2):

250 = 50t

t = 5 seconds .