An Object Is Placed on a Board

Multiple Choice

An object is placed on a board. The coefficient of static friction between the object and the board is 0.40. One end of the board is slowly raised until the object begins to slide. The angle that the board makes when the object begins to slide is

A) 16°.
B) 22°.
C) 74°.
D) unknown; the answer cannot be determined without knowing the mass of the object.