Friction

Newton’s first law of motion: Friction8SCIENCE

Types of friction• What is friction?– Unbalanced force that slows objects down

• Important to understand to use Newton’s laws as friction in almost all real-life situations

Types of friction:• Static friction• Sliding friction• Rolling friction• Air resistance

Static friction

• Friction prevents an object from moving when force is applied

• Tries to keep an object at rest• Ex: walking– Every step you take pushes

against the Earth– Without friction, you would

slip and fall with each step

• What happens when the net force is greater then the force of static friction?

Sliding friction

• Slows down an object that slides• Ex: if you push a box across the room, there is

sliding friction between the bottom of the box and the floor

• Ex: Rubbing hands , shuffling shoes

Types of Friction

ROLLING FRICTION• Allows wheels to turn by

pushing back so tire moves forwards– Ex: bicycle, car

• Ex: when you ride your bike through water, there may not be enough friction between the tire and the ground to move forward, and so the bike skids (slides off balance)

AIR RESISTANCE• Air pushes against you• Acts on the forward-moving

part an object– Ex: front of a car

• Ex: when you ride the bicycle, the air pushes the your hair and clothes back