Question

What is the co-efficient of friction for lubricant?

(a) Cf = \(\frac{ZN}{P} \)

(b) Cf = \(\frac{PN}{Z} \)

(c) Cf = \(\frac{ZP}{N} \)

(d) Cf = ZPN

The question was posed to me by my college director while I was bunking the class.

This intriguing question originated from I.C Engine topic in division Internal Combustion Engine of Farm Machinery

Answer 1

Right choice is (a) Cf = \(\frac{ZN}{P} \)

For explanation I would say: The lubricated friction depends on the operating conditions such as the sliding speed, lubricant viscosity, temperature etc. In the formula, Z is the viscosity or oil thickness, N is the surface speed and P is the pressure caused by the weight.