A Window Washer Attempts to Lean a Ladder Against a Frictionless

Multiple Choice

A window washer attempts to lean a ladder against a frictionless wall. He finds that the ladder slips on the ground when it is placed at an angle of less than 75 $\degree$ to the ground but remains in place when the angle is greater than 75 $\degree$ . The coefficient of static friction between the ladder and the ground:

A) is about 0.13
B) is about 0.27
C) is about 1.3
D) depends on the mass of the ladder
E) depends on the length of the ladder