Question

A metal plate 5cm×5cm rest on a layer of castor oil 1mm thick whose coefficient of viscosity is 1.55Nsm^(-2). Find the horizontal force required to move the plate with a speed of 2 cms^(-1).

(a) 0.775N

(b) 0.0577N

(c) 0.0775N

(d) 0.577N

This question was addressed to me during an online exam.

My question is from Streamline and Turbulent Flow topic in division Thermal Properties of Matter of Engineering Physics I

Answer 1

The correct answer is (c) 0.0775N

For explanation: F=ȠA dv/dx

F=1.55×25×10^-4×(2×10^-2)/(1×10^-3)=0.0775N.