Question

A man drops a ball downside from the roof of a tower of height `400` metres. At the same time another ball is thrown upside with a velocity `50 "meter"//sec` from the surface of the tower, then they will meet at which height from the surface of the tower.
A. 100 metres
B. 320 metres
C. 80 metres
D. 240 meters

Answer 1

Correct Answer - C
Let both balls meet at point `P` after time `t`.
The distance travelled by ball `A, h_1 = (1)/(2) g t^2`
The distance travelled by ball `B, h_2 = ut- (1)/(2) g t^2`
`h_1 + h_2 = 400 m`
`rArr ut = 400, t = 400//50 = 8 m`
`:. h_1 = 320 m and h_2 = 80 m`.