Question

A mass of 4kg rests on a horizontal plane. The plane is gradually inclined until at an angle θ= 15° with the horizontal, the mass just begins to slide. What is the coefficient of static friction between the block and the surface?

(a) 0.814

(b) 0.27

(c) 1.5

(d) 3.5

This question was addressed to me in homework.

This interesting question is from Friction and Forces in portion Laws of Motion of Engineering Physics I

Answer 1

Right option is (b) 0.27

Easy explanation: θ = 15° is the angle of response.

Coefficient of friction, μ = tan θ = tan 15° = 0.27.