Question

A capillary tube has a diameter of 3 mm and 100 mm length. A head of 10 cm of oil above the inlet of the capillary maintains a pressure difference across the capillary. The specific gravity of oil is 0.92. A volume of 300 cm^3 of oil passes through the in 10s. What will be the viscosity of oil?

(a) 5.68 * 10^-4 poise

(b) 5.98 * 10^-4 poise

(c) 5.68 * 10^-5 poise

(d) 5.98 * 10^-5 poise

This question was posed to me in an interview for job.

My question is from Cooling System in chapter Fuel Supply and Cooling System of Farm Machinery

Answer 1

Right option is (b) 5.98 * 10^-4 poise

The explanation is: p = ρgh

P = 0.92 * 981 * 1

P = 902.52 dyne/cm^2

Now,

η = \(\frac{π p r^4 t}{8Vl} = \frac{[π*902.52*(0.15)^4*10]}{8*300*10}\) = 5.98 * 10^-4poise.