What is the direction of friction when an object is about to move to the left?

What is the direction of friction when an object is about to move to the left?

• A. Friction to the left
• B. Friction to the right
• C. No friction
• D. Friction upward

Answer: (B)

Friction always opposes the motion (or the tendency to move) between surfaces. If the push tries to move the object to the left, the frictional force acts to the right to resist that leftward tendency. At the point just before slipping, this friction is at its maximum static value but still directed opposite to the impending motion. Only if the push exceeds that limit would the object actually move left, and then kinetic friction would continue acting to the right. So the frictional direction in this situation is toward the right.

Friction always opposes the motion (or the tendency to move) between surfaces. If the push tries to move the object to the left, the frictional force acts to the right to resist that leftward tendency. At the point just before slipping, this friction is at its maximum static value but still directed opposite to the impending motion. Only if the push exceeds that limit would the object actually move left, and then kinetic friction would continue acting to the right. So the frictional direction in this situation is toward the right.