Friction: Page 83
QUESTION: When would you want to create friction?
OBJECTIVE: Students will be able to name and give everyday examples
of the four types of friction.
VOCABULARY: friction
rolling friction
static friction
fluid friction
sliding friction
Friction
Write these questions onto page 83
SKIP ONE LINE BETWEEN EACH QUESTION
1.
2.
3.
4.
Which direction does friction work?
What two factors determine the amount of friction?
What are the four different types of friction?
Give two common examples of when friction isn’t bad.
What causes friction?
Whenever two surfaces touch one another friction is created.
Friction works opposite the motion of the object.
a baseball player sliding into 2nd base.
a ball rolling in the grass.
a surfboard against a wave
All of these everyday events are examples of friction.
What determines the amount of friction?
Two factors can change the amount of friction.
1. how hard the surfaces are rubbing against one another
2. the type of surfaces
Example 1: The fast spinning
tires of a racecar will create
more friction than the tires on
your family car.
Example 2: More friction will
be created between a person
sliding in dirt than sliding on
water.
What are the four types of friction?
Static Friction
Sliding Friction
Rolling Friction
Fluid Friction
Static Friction
Static friction is the most difficult to understand.
A goat standing on the side of a hill is being kept
in place by the static friction between his hooves
and the hill. If there wasn’t enough static
friction, the goat would be pulled down the hill
by gravity.
Sliding Friction
Sliding friction can be seen hundreds of times a day.
If there wasn’t enough sliding friction between your gym shoe and
the floor, you would slip all over the place.
Rolling Friction
Rolling friction involves round objects.
Wheels are often put on heavy objects
like refrigerators so they can be rolled
around instead of dragged. Rolling
friction is usually less than sliding
friction.
The tires on a car provide friction to
start and stop the car.
Fluid Friction
Fluid friction is also very common.
Air and water are the two most common fluids. Solid objects are
shaped in a way that allows them to slice through air and water rather
than push through them.
Is Friction Always Bad?
Friction causes two things to happen.
Friction causes heat. The more friction, the more heat. This isn’t
usually good.
When the Space Shuttle returns to Earth the
air causes enough friction to burn it up. .
Friction slows down athletes when they
race. So they are always looking for ways to
reduce friction.
Although friction causes moving objects to slow
down, this isn’t always bad
If there was no friction you would not be able to
stop your bicycle, your car or yourself.
Friction: page 83
Check that the answers to these
questions are in your notes.
1.
2.
3.
4.
Which direction does friction work?
What two factors determine the amount of friction?
What are the four different types of friction?
Give two common examples of when friction isn’t bad.
VOCABULARY
Friction-the force created when two surfaces rub against each other.
Static friction-a force that acts on two surfaces touching, but not
moving.
Sliding friction-a force that acts when two solid surfaces slide past
one another.
Rolling friction-a force that acts when one surface rolls against
another surface.
Fluid friction-a force that acts when a solid moves through a liquid.