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

`r=0.3mm=3xx10^(-4)m`
`eta=1.8xx10^(-5)Nms^(-2)`
Terminal velocity `v_(t)=(?)`
`v_(t)=(2)/(9)(r^(2)g(rho-rho_(o)))/(eta)`
`rho` = density of water `=10^(3)kg//m^(3)`
`rho_(o)`=neglecting air density
`v_(t)=(2)/(9)((9xx10^(-8))(9.8)(10^(3)))/(1.8xx10^(-5))`
`=10.88`
`v_(t)=10.9m//s`