Neglecting the density of air ,the terminal velocity obtained by a raindrop of radius 0.3 mm falling through air of viscosity `1.8xx10^(-5)Nsm^(-2)` will be ….

Options

A. `10.9ms^(-1)`
B. `7.48ms^(-1)`
C. `3.7ms^(-1)`
D. `12.8ms^(-1)`

Answer

a

Explanation

The terminal velocity of the spherical raindrop of radius r is given by ,
`v_(t)=(2r^(2)rhog)/(9eta)`, where `rho` is the density of water and `eta` is the viscosity of air , density of air `rho_(o)=0`
`r=0.3mm=0.3xx10^(-3)m,rho=10^(3)kg//m^(3)`,
`g=9.8ms^(2)`
`andeta=1.8xx10^(-5)Ns//m^(2))`.Hence,
`v_(t)=(2xx(0.3)^(2)xx10^(-3)xx9.8)/(9xx1.8xx10^(-5))=10.9ms^(-1)`