First slide

Viscosity

Question

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

Moderate

A

0.1 m/s
B

0.4 m/s
C

0.133 m/s
D

0.2 m/s

Solution

Terminal speed of spherical body in a viscous liquid is given by
$v_{T} = \frac{2 r^{2} (ρ - σ) g}{9 η}$
where $ρ$ = density of substance of body and
$σ = density of liquid .$
From given data
$\frac{v_{T} (Ag)}{v_{T} (Gold)} = \frac{ρ_{Ag} - σ_{1}}{ρ_{Gold} - σ_{1}}$
$\Rightarrow v_{T} (Ag) = \frac{10.5 - 1.5}{19.5 - 1.5} \times 0.2 = \frac{9}{18} \times 0.2 = 0.1 m / s$

Get Instant Solutions

When in doubt download our app. Now available Google Play Store- Doubts App

Recieve an sms with download link

Doubts App

OR

SCAN ME

Doubts App

Doubts App