Question

The maximum average velocity of water in a tube of diameter 2 cm so that the flow becomes laminar is (The viscosity of water is 10⁻³ Nm⁻² s¹)

Options

• 0.1 ms⁻¹

• 1 ms⁻¹

• 10 ms⁻¹

• 100 ms⁻¹

Answer 1

0.1 ms⁻¹

Explanation:

V_c = `"N" η/"ρD"`

For laminar flow, Reynold's number,

N = 2000,  η = 10⁻³ NM⁻² s⁻¹

∴ V_c = `(2000 xx 10^-3)/(10^3 xx 2 xx 10^-2)`

= 0.1 m/s