surfaces in contact are at rest gravity move through liquid or gas sliding weight sandpaper carpet gravel ex. SF combing hair, writing mass surfaces in motion ice glass tile replace sliding with rolling RF ex. riding a bike, bowling rolling static FF ex. airplane, swimmer less force pushing together fluid ex. SF a book resting on a desk add a lubricant like oil, wax or grease friction friction harmful smooth the surface increases as the speed of the object increases friction force direction Law of Universal Gravitation friction helpful surfaces in contact are at rest gravity move through liquid or gas sliding weight sandpaper carpet gravel ex. SF combing hair, writing mass surfaces in motion ice glass tile replace sliding with rolling RF ex. riding a bike, bowling rolling static FF ex. airplane, swimmer less force pushing together fluid ex. SF a book resting on a desk add a lubricant like oil, wax or grease friction friction harmful smooth the surface increases as the speed of the object increases friction force direction Law of Universal Gravitation friction helpful
(Print)
surfaces in contact are at rest
gravity
move through liquid or gas
sliding
weight
sandpaper carpet
gravel
ex. SF combing hair, writing
mass
surfaces in motion
ice
glass tile
replace sliding with rolling
RF ex. riding a bike, bowling
rolling
static
FF ex. airplane, swimmer
less force pushing together
fluid
ex. SF a book resting on a desk
add a lubricant like oil, wax or grease
friction
friction harmful
smooth the surface
increases as the speed of the object increases
friction
force
direction
Law of Universal Gravitation
friction helpful
