High School Physics

# Three things are worth noting about frictional forces

Three things are worth noting about frictional forces: these fundamental points will help you to understand friction as a force, answer questions from the friction chapter and solve numerical problems based on friction. Here are the points:

1. The smaller µ is, the more slippery the surface. For instance, ice will have much lower coefficients of friction than Velcro. In cases where µ=0 , the force of friction is zero, which is the case on ideal frictionless surfaces.
2. The coefficient of kinetic friction is smaller than the coefficient of static friction. That means it takes more force to start a stationary object moving than to keep it in motion.
3. Frictional forces are directly proportional to the normal force. That’s why it’s harder to slide a heavy object along the floor than a light one. A light coin can slide several meters across a table because the kinetic friction, proportional to the normal force, is quite small.