Question

A layer of oil 1.50 mm thick is placed between two microscope slides. researchers find that a force of 5.50Ã10â4 n is required to glide one over the other at a speed of 1.00 cm/s when their contact area is 6.00 cm2. what is the oil's viscosity? what type of oil might it be?

Answer 1

Force to slide the two surface over each other is given as

$F = \eta A \frac{dv}{dx}$

as we know that

$F = 5.50 \times 10^{-4} N$

$A = 6 \times 10^{-4}$

$\frac{dv}{dx} = \frac{1\times 10^{-2}}{1.50 \times 10^{-3}}$

now plug in all data in above formula

$5.50 \times 10^{-4} = \eta 6 \times 10^{-4} \frac{1 \times 10^{-4}}{1.50 \times 10^{-3}}$

$\eta = 0.1375 Pa s$

This is approximate range of Motor Oil