From a height of 20 m above a horizontal floor, a ball is thrown down with initial velocity 20 m/s . After striking the floor , the ball bounces to the same height from which it was thrown. Find the collision between the ball and the floor .

Explanation

Here u= 20 m/s h = 20 m, g `= 10m//s^(2)`
Using, `v^(2) - u^(2) = 2as`
`u_(1)^(2) - 20^(2) = 2 xx 10 xx 10`
`u_(1)^(2) = 20^(2) + 400 = 400 + 400`
`:. u_(1) = sqrt(800)`