UPSC Civil Service Exam Questions - Engineering

Q1:

In the figure shows two blocks of equal weights designated as W1 and W2 connected together by a rod and resting on an inclined plane whose angle α can be varied. The coefficients of friction between the blocks and the surface of the plane are μ1 = 0.2 and μ2 = 0.3. The value of angle α at which the slipping will commence is given by

A tan α = 0.1

B tan α = 0.2

C tan α = 0.25

D tan α = 0.8

ANS:C - tan α = 0.25

(μ1+μ2)/2 = 0.25.