﻿
Question
Mon May 23, 2011

# From the top of the tower 100m in height a ball is dropped and at the same time another ball is projected vertically upward from the ground with velocity of 25m/s. Find when and where the 2 balls meet(a=9.8m/s2

Mon May 23, 2011

They will meet instinctively. Here's how.

Lets take distance covered by the stone thrown upwards to meet the other as x. Then the other stone covers a distance of (100-x)m.

Let the ball dropped down be b1. So the ball thrown up is b2.

b1 => d = 100-x

g = 9.8 m/s sq.

u = 0

We know, s= ut + 1/2at sq.

Putting values,

100-x = 4.9t sq.                  ....(1)

b2 => d = x

g = -9.8 m/s sq.

u = 25 m/s

We know, s= ut + 1/2at sq.

Putting values,

x = 25t -4.9t sq.                  ....(2)

100-x +x = 4.9t sq. + 25t - 4.9t sq.

t = 4 secs.

Puuting t = 4 in (1),

100-x = 4.9t sq.

100-x =19.6

x = 80.4 m

So, they meet at  80.4 m from ground after 4 seconds.

Related Questions
Mon August 29, 2016

# A bird moves with velocity 20m/s in a direction making an angle of 60 degree with the eastern line and 60 degree with vertical upwards. The velocity vector in rectangular form :   a) 10 i + 10 j + 10 k   b) 10 i +10(2)^1/2  j + 10 k   c) -20 i +10(2)^1/2  j + 20 k   d) 10(2)^1/2 i + 10 j + k

Mon August 29, 2016

﻿