A spherical ball of radius `3xx10^(-4)`m and density `10^(4)kg//m^(3)` falls freely under gravity through a distance h before entering a tank of water. If after entering the water the velocity of the ball does not change, find h the viscosity of water is `9.8xx10^(-6)N-s//m^(2)`

Answer

20.4 m

Explanation

`V_(T)=(2)/(9)(r^(2)(rho-sigma)g)/(eta)`
`=(2)/(9)xx((1xx10^(-4))^(2)xx(10^(4)-10^(3))xx9.8)/(9.8xx10^(-6))`
`V_(T)=20m//s`
for free falling body
`V=sqrt(2gh) implies h=(V_(T)^(2))/(2g) implies h =20.4m`