Question

A body, resting on a rough horizontal plane required a pull of 181 N inclined at 30° to the plane just to move it. It was recorded that a push of 220 N inclined at 30°° to the plane just moved the body. Estimate the coefficient of friction.

(a) 0.17

(b) 0.2

(c) 0.5

(d) 0.75

This question was addressed to me in my homework.

This intriguing question originated from Limiting Friction topic in section Friction of Machine Kinematics

Answer 1

The correct option is (a) 0.17

To explain I would say: For vertical equilibrium we have reaction R = W – 181sin30

horizontally,

f = 181cos30

Now considering a push of 220N

horizontally

f = 220cos30

vertically

R = W + 220sin30

solving the equations we get

μ = 0.171.