👟 STATIC VS KINETIC FRICTION
PAGE 1 OF 5, WHAT IS FRICTION?
THE GRIP BETWEEN SURFACES
WHY YOUR SHOES DON'T SLIDE
Friction is the force that resists sliding when two surfaces touch. Even smooth-looking objects are bumpy at the microscopic level. Those tiny peaks and valleys interlock, creating grip. Without friction you could not walk, write, or pick up a glass. Every step you take relies on your shoe pushing backward against the ground, and friction pushing forward to move you ahead. Friction is not always your enemy. It is the reason cars can accelerate and brakes can stop.
📐 FRICTION FORMULA
f = μN. Friction force equals the coefficient of friction μ times the normal force N pressing the surfaces together.
GRIP!
NORMAL FORCE
⬆️ N = surface push-back on object
→ Heavier object = more friction
📦 More weight = tighter contact
→ Heavier object = more friction
📦 More weight = tighter contact
COEFFICIENT μ
🧊 Ice: low μ, slippery
🏀 Rubber on dry road: high μ
🔬 Depends on both materials
🏀 Rubber on dry road: high μ
🔬 Depends on both materials