Given, ρg=19.5 g/cm3 (density of gold)
ρl=1.5 g/cm3 (density of liquid)
ρs=10.5 g/cm3 (density of silver)
Terminal speed of sphere of sphere of gold, vg=0.2 m/s
Let the terminal speed of sphere of silver =vs
Terminal velocity of any body is given by (v)=2(ρb−ρl)r2g9μ
Both sphere of gold & silver are of same size.
So, Terminal velocity ∝(ρb−ρl)
where ρb= density of spheres
ρl = density of liquid
∴vgvs=(ρg−ρl)(ρs−ρl)
⇒0.2vs=(19.5−1.5)(10.5−1.5)
⇒vs=0.1 m/s