Friction
An opposing force that effects us everyday
First, remember what a force is!!
o Force: push or a pull on an
object
3 Characteristics
1. Have size
2. Have direction
3. Have units
What is Friction Then?
o Friction: a force that opposes
motion between two surfaces
that are touching
There is NO SUCH
THING as a completely
smooth surface!!
The Source of Friction
o The surface of any object
There are
microscopic hills
and valleys on the
surface of every
object
As the surfaces move back and forth, the hills
and valleys stick to one another
What Controls The Amount of Friction?
o 2 Major Factors
1. Roughness of surfaces
o Rougher the surface = more
friction
2. Force pushing the objects together
o Greater the force = more
friction
2 Types of Friction
o Sliding Friction
Requires a great amount of force to
move the object
2 Types of Friction
o Rolling Friction
Requires much less force to move the
object
How Can We Increase and Decrease
Friction?
o Decrease Friction
Lubricants: substances
that are applied to
surfaces to reduce friction
between them
How Can We Increase and Decrease
Friction?
o Increase Friction
1. Increase the
force acting on
the object
2. Increase the
roughness of the
surface