A spherical body of radius r and density σ falls freely through a viscous liquid having density ρ and viscosity η and attains a terminal velocity…

A spherical body of radius $\displaystyle r$ and density $\displaystyle \sigma$ falls freely through a viscous liquid having density $\displaystyle \rho$ and viscosity $\displaystyle \eta$ and attains a terminal velocity $\displaystyle v_0$. Estimated maximum error in the quantity $\displaystyle \eta$ is : (Ignore errors associated with $\displaystyle \sigma, \rho$ and $\displaystyle g$, gravitational acceleration)