An iron ball of radius 0.2 cm and density 7.8 g/cm""^(3) falls through a tank of oil of density =1.5 xx 10^(3)" kg/m"^(3) and viscosity 9.92 poise. What will the terminal velocity of the iron ball in the oil? Also, determine its terminal velocity in water of viscosity 10^(-3)" Nsm"^(-2).

An iron ball of radius 0.2 cm and density 7.8 g/cm""^(3) falls through

1.	An iron ball of radius 0.2 cm and density 7.8 g/cm""^(3) falls through a tank of oil of density =1.5 xx 10^(3)" kg/m"^(3) and viscosity 9.92 poise. What will the terminal velocity of the iron ball in the oil? Also, determine its terminal velocity in water of viscosity 10^(-3)" Nsm"^(-2).
Answer» <P> Solution :Given, r=0.2 CM `p_(i)=7.8 g//cm^(3)` `p_(0)=1.5 xx 10^(3) kg//m^(3)=1.5 g//cm^(3)` `eta=99/2 Nsm^(-2)` Terminal velocity of iron ball in oil is `V=(2r^(2) g(p_(i)-p_(o)))/(9eta)` `=(2 xx (0.2)^(2) xx 980 xx (7.8-1.5))/(9 xx 9.92)` =5.53 cm/s Terminal velocity of iron ball in water `p_(W)=10^(3) kg//m^(3)=1 g//cm^(3), eta=10^(-3) Nsm^(-2)` `=10^(-2) "poise"` `v^(2)=(2r^(2) g(p_(i)-p_(w)))/(9 eta)` `=(2 xx (0.2)^(2) xx 980 xx (7.8 -1))/(9 xx 10^(-2))` =5923.55 cm/s