Question

A spherical ball of iron of radius 2 mm is falling through a column of glycerine. If densities of glycerine and iron are respectively 1.3 × 10³ kg/m³ and 8 × 10³ kg/m³. η for glycerine = 0.83 Nm^-2 sec, then the terminal velocity is ______.

Options

• 0.7 m/s 

• 0.07 m/s

• 0.007 m/s

• 0.0007 m/s

Answer 1

A spherical ball of iron of radius 2 mm is falling through a column of glycerine. If densities of glycerine and iron are respectively 1.3 × 10³ kg/m³ and 8 × 10³ kg/m³. η for glycerine = 0.83 Nm^-2 sec, then the terminal velocity is 0.07 m/s.

Explanation:

Terminal velocity, v₀ = `(2"r"^2(rho-rho_0)"g")/(9eta)`

= `(2xx(2xx10^-3)^2xx(8-1.3)xx10^3xx9.8)/(9xx0.83)`

= 0.07 ms^-1