A rain drop with radus 1.5 mm falls from a cloud at a height 1200 m from ground . The density of water is 1000 `kg//m^(3)` and density of air is `1.2 kg//m^(3)`. Assume the drop was spherical throughout the fall and there is no air drag. The impact speed of the drop will be :

Options

A. `27 km/h`
B. `550 km/h`
C. Zero
D. `129 km/h`

Answer

`(2)`

Explanation

`(mg - V rho_(a)g)h = 1/2 mv^(2)`
`(rho_(w) - rho_(a))Vgh = 1/2V rho_(w)v^(2)`
`(rho _(w) - rho_(a))gh = 1/2 rho_(w)v^(2)`