Question

if a ball is thrown downward of a 100m high building ... at what speed the ball will reach the ground​

Answer 1

Answer:

For first ball,

Time taken to reach mid-way

t=2hg−−√=2×5010−−−−√=10−−√s [∵h=1002m]

For second ball, using v=u+at

v=0,a=−g,u=?

Let t' be time taken by the ball to reach midway.

∴0=u−gt′ort′=ug=u10

As both the balls collide at same time so

(t−0) = (t′−0) ort = t′

√10=u/10;u=10√10=31.6ms−1.