A ball is dropped from a building of height 45 m. Simultaneously another ball is thrown up with a speed 40 m/s. Calculate the relative speed of the balls as a function of time.

Explanation

For the ball dropped from the building , `u _(1) =0`
For the ball thrown up,` u _(2) = 40 m//s`
Velocity of the dropped ball after time t,
`v _(1) = u _(1) + g t`
`v _(1) = g t` (downward) `" "…(1)`
For the ball thrown up, `u _(2) = 40 m//s`
Velocity of the ball after time t
`v _(2) = u _(2) -0 g t = (40 - g t) ` upward) `" "...(2)`
Relative velocity of one ball w.r.t. another ball
`= v _(1) - v _(2)`
`- g t[-[- (40-g t)] (because `From (1) and (2)) = 40 m.s