
2 Properties of the static friction force
Point 2 of 8 — Lesson 1: Equilibrium of a Particle, Friction and Limiting Static FrictionQuestion bank: 3 questions (3 with pictures)
02 2 Properties of the static friction force
Properties
- Direction: static friction opposes sliding; it acts opposite to the direction in which the body tends to slide.
- Magnitude: equals the tangential (sliding) force that tries to move the body, and it stays equal to it as long as the body is balanced.
- Growth: as the tangential force increases, increases, until it reaches a maximum value that it cannot exceed.
- At that stage the body is about to slide, and the friction is called the limiting static friction .
- Therefore .
Coefficient of static friction
- The ratio between the limiting friction and the normal reaction is constant for two given surfaces. It is the coefficient of static friction :
- It depends on the nature of the surfaces, not on the shape of the contact area or on the masses.
- Use only when the body is about to move; otherwise find from the equilibrium equations.
📝 Question bank for this point
3 questions linked to this point only, 3 of them with pictures.