Problem $2$: Reynolds Number

$($a$)$Given that the frictional force on a spherical bead of radius R moving with velocity v through a fluid of viscosity is $6$Rv$,$ calculate the Reynolds number for a bead of radius R and density $1,$ falling at its terminal velocity through a liquid of viscosity and density $2.$

$($b$)$Estimate the Reynolds number for $3$ mm$-$diameter Delrin $($polyoxymethylene$)$ beads $($$11\mathrm{.}4$ g cm$3),$ falling at their terminal velocity in canola oil $($$20\mathrm{.}9$ g cm$3,$ $60$ mPa s$).$ Do you expect laminar or turbulent flow in this case?