A pobble is thrown vertically upwards from a bridge with an initial velocity of `4.9 ms^(-1)` . It strikes the water after 2 s. If acceleration due to gravity does the pebble strike the water ?

Explanation

Let height of the bright be h, then
`h=-4.9xx2+(1)/(2)xx9.8xx(2)^(2)rArr h=9.8 m`

velocity with which ball will hit the ground
`v=u+At rArr v=-4.9+9.8xx2=14.7 ms^(-1)`