A pebble is thrown vertically upwards from a bridge with an initial velocity of 4.9 m/s. It strikes the water after 2s. If acceleration due to gravity is `9.8 m//s^(2)(a)` what is the height of the bridge? (b) with what velocity does that pebble strike the water?

Explanation

Let height of the bridge be h then
`h = -4.9 xx 2 + (1)/(2) xx 9.8 xx (2)^(2)`
`rArr h = 9.8 m`
velocity with which the ball strikes the water surface
`v = u + at`
`rArr v = - 4.9 + 9.8 xx 2 = 14.7 m//s`