State six laws of friction
1. Friction is always parallel to the contact surface and in the opposite direction to the force tending to produce or producing motion.2. Friction depends on the nature of the surfaces and materials in contact with each other.3. Sliding (kinetic) friction is less than static friction (friction before the body starts to slide).4. Kinetic friction is independent of speed.5. Friction is independent of the area of contact.6. Friction is proportional to the force pressing the two surfaces together.