Designed for Heat (Expansion and Contraction)

UNIT 5 ENERGY

Expansion and Contraction

TURN & TALK

What are these
and what are
they used for?

AumSum Kids: Thermal Expansion

EXPANSION & CONTRACTION

When heat is added to a substance
(solid, liquid, or gas), the molecules
and atoms vibrate faster.
As the molecules vibrate faster, the
space between them increases. This
can make the substance expand
and take up more space.
If the motion and spacing increases
enough, the substance can change
its state of matter. However, the
mass will always remain the same.

When heat leaves a substance, the
molecules will vibrate slower.
The molecules will get closer which results
in the matter contracting. Again, the
mass will be the same.

EXPANSION & CONTRACTION

WHY IS THIS IMPORTANT
TO KNOW?
When objects heat up
and expand…
Railroad tracks can
buckle!
Which is why tracks
now have gaps built in.

EXPANSION & CONTRACTION

WHY IS THIS IMPORTANT
TO KNOW?
When objects heat up
and expand…
Bridges can crack!
Which is why bridges
now have expansion
points.

EXPANSION & CONTRACTION

WHY IS THIS IMPORTANT
TO KNOW?
When objects heat up
and expand…
They can help you
when you get stuck!

EXPANSION & CONTRACTION

TURN & TALK

What are these and

how are they formed?

Normally, objects contract
as they get colder, but
remember,
water breaks
the rules!

I break

the rules!

EXPANSION & CONTRACTION

WHY IS THIS IMPORTANT
TO KNOW?
When water freezes,
then expands…
It can burst pipes!

EXPANSION & CONTRACTION

WHY IS THIS IMPORTANT TO KNOW?

When water freezes, then expands…

It can cause cracks and pothole in the road.

EXPANSION & CONTRACTION

WHY IS THIS IMPORTANT
TO KNOW?
When water freezes,
then expands…
It becomes less dense,
and can float!

EXPANSION & CONTRACTION

Multiple Choice

What is Thermal expansion?

• The transfer of thermal energy between materials by the collisions of particles 

• Is a decrease in a materials volume when temperature decreases 

• An increase in a materials volume when temperature increases

• Chicken fried rice

Multiple Choice

If the atoms of an object are moving or vibrating fast, the temperature would be...

• Hot

• Cold

• Unknown

Multiple Choice

If the atoms of an object are moving or vibrating slow, the object would feel...

• Cold

• Hot

• Unknown

Multiple Choice

Many objects, such as train tracks and road joints, are specifically designed to allow extra space for ...

• thermal energy

• specific heat

• thermal expansion

• conductors

Multiple Choice

When objects contract upon cooling...

• volume increases and density increases.

• volume increases and density decreases.

• volume decreases and density decreases.

• volume decreases and density increases.

Multiple Choice

Objects gain heat and _________. 

• expand

• contract

Multiple Choice

What is Thermal Contraction 

• A Potato

• A decrease in a materials  volume when its temperature decreases 

• The movement of fluids in a cycle because of convection 

• A material through which  thermal energy does not flow easily.