Question

A body of mass M starts sliding down on the
inclined plane where the critical angle is
ACB = 30° as shown in figure. The coefficient of
kinetic friction will be
(1) Mg/√3
(2) √3 Mg (3) √3
(4) None of these​

Answer 1

Answer:

4 because i think the questions demand is not full

Answer 2

Answer:

(4) None of these​

Explanation:

Given that

Critical angle =  30°

At the critical condition

mg sinθ = μ mg cosθ

sinθ =  μ cosθ

so we say that

tan θ=  μ

 μ= 0.577

coefficient of  kinetic friction =0.577

So our option (4)      is correct

Option 1 and 2 are conceptually wrong because we know that coefficient of friction is a dimension less quantity but option 1 and 2 have dimension of force.