If the terminal speed of a sphere of gold (density `=19.5kg//m^3`) is `0.2m//s` in a viscous liquid (density `=1.5kg//m^3`), find the terminal speed of a sphere of silver (density `=10.5kg//m^3`) of the same size in the same liquid

Options

A. 0.133 m/s
B. 0.1 m/s
C. 0.2 m/s
D. 0.4 m/s

Answer

B

Explanation

`v=2/9 (r^2 g(rho-sigma))/(eta)`
`implies v prop (rho-sigma)`
`implies (v_G)/(v_S)=(19.5-1.5)/(10.5-1.5)=(18)/(9)=2`
`implies v_S=(v_G)/(2)` =0.1 m/s