An object falls from a bridge that is 45 m above the water.It falls deirectly into a small row-boat moving with constant velocity that was 12 m from the point of impact when the object was released .What was the speed of the boat?

Explanation

Boat velocity `v=(s)/(t)`,But s=12m
`therefore t=(s)/(u)=(12)/(v)` …….(1)
Ball has fallen from a height of 45 m,u=0
`S=ut+(1)/(2)at^(2)`
`45m=0+(1)/(2)"gt"^(2)=(1)/(2)xx10xx((12)/(v))^(2)`
`v^(2)=(1)/(2)xx10xx(144)/(45)=(720)/(45)`
`v^(2)`=16
`therefore` v=4 m/s