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

B

Explanation

Impact speed -
`v=sqrt(2gh)=sqrt(2xx9.8xx1200)`
= 153.36 m/s
= 552 km/h
`~~` 550 km/h
Note: For height (h) = 1200m, Value of g does not change significantly. So we use this formula.