**Example 4:** The block has a mass of 100
kg. If the coefficient of static friction between the block and the
surface is 0.25, determine

b. the angle of static friction.

c. Is tipping a possibility?

**Solution:**

Part a: We begin by drawing the free-body diagram of the block and writing the two force equilibrium equations.

Since the condition is impending slipping, the friction force is related to the normal force as

Substituting for F and solving the two equilibrium equations gives

Part b: the angle of static friction is the angle of the resultant force at the surface of contact, and is found as

Part
c: To determine if tipping is a possibility, we solve for
h_{max} and compare it to h= 60 in. Using the equilibrium of moments, we
find

Since h_{max}>h, no tipping will occur.