Question

Use the equation mg sin A = umg cos A to determine the angle at which a waxed wood block on an inclined plane of wet snow begins to slide. Assume the coefficient of friction, u, is 0.17. 9.6º 42º 48º 22º

Answer 1

Draw a diagram to illustrate the problem as shown below.

The weight, mg, is resolved into mg cos(A) and mg sin(A).
g = 9.8 m/s², acceleration due to gravity
μ = 0.17, static coefficient of friction

For motion to be initiated,
mg sinA = μN
or
mgsin(A) = μmg cos(A)
sin(A)/cos(A) = μ
tan(A) = μ = 0.17
A = tan⁻¹ 0.17 = 9.648° = 9.6° (approx)

Answer: 9.6°