Question

A board is balanced on a rough horizontal semicircular log. Equilibrium is obtained with the help of addition of a weight to one of the ends of the board when the board makes an angle θwith the horizontal. Coefficient of friction between the log and the board is

• A. tanθ
• B. cosθ
• C. cot θ
• D. sin θ

Answer 1

Answer: (A)

tanθ

Answer 2

Let m_b be the mass of board and m be the mass placed at one end of the board.

Then for equilibrium

μN cos θ = N sin θ

i.e., μ = tan θ