Two rain drops of same radius r falling with terminal velocity v merge and from a bigger drop of radius R. The terminal velocity of the bigger drop is

Options

A. `vR/r`
B. `vR^2/r^2`
C. v
D. 2v

Answer

B

Explanation

Terminal velocity , `v=2/9(r^2(rho-sigma)g)/(eta)`
`therefore v prop r^2 rArr v/V = r^2/R^2 rArr V=(vR^2)/(r^2)`