Review Unit 3 Energy: Conservation and Transfer

Lesson 19

Congratulations! We have finished Unit 3 Energy: Conservation and Transfer. Now it is time to review

what we learned.

Take out your K-W-L chart in your notebook and as we review write what you learned from this unit on force and motion. Write it in the What I Learned section.

Does heat energy behave in predictable ways?

Yes, heat energy does behave in predictable ways. Heat will

always flow in one direction from hot to cold.

When there is a temperature

difference, heat will

always move from higher to

lower temperatures.

How does heat move from one place to another?

Heat can move from one place to another by three methods:

conduction in solids, convection of fluids (liquids or gases), and

radiation through anything that will allow radiation to pass.

How do we explain conduction?

Conduction occurs when two objects

at different temperatures are

in contact with each other. Heat

flows from the warmer to the cooler object until they are

both at the same temperature.

Conduction is the transfer of thermal

energy between

things that are touching.

The two objects here are the fire and the metal. The metal is touching the fire and will slowly heat up until it is the same temperature as the

fire.

Conduction can happen within one object. (For example, thermal energy can be conducted through the handle of a metal pot.)

How do we explain convection?

Convection is the movement of thermal energy by the

movement of liquids or gases.

Convection occurs when warmer areas of a liquid or gas rise to

cooler areas in the liquid or gas.

As this happens, cooler liquid or gas takes the place of the warmer

areas which have risen higher.

You see convection when

you boil water in a pan. The bubbles of water that rise

are the hotter parts of the water rising to the cooler

area of water at the top of the pan.

Convection in the oceans and

atmosphere helps to move thermal energy around Earth, and is an important factor

influencing weather and

climate.

How do we explain radiation?

Radiation is a form of energy transport consisting of

electromagnetic waves traveling at the speed of light.

Radiation is a method of heat

transfer that does not rely

upon any contact between the

heat source and the heated

object.

The Sun is the main source of electromagnetic energy on Earth.

Part of this energy, light, is used by producers to make food.

Radiation can also happen in other circumstances. Examples of

radiation would be sitting in front of a fireplace or a heater.

How can heat change the properties of a substance?

All matter is made up of atoms.

As matter heats, the atoms become more active (since heat is energy), thus making the atoms

move more freely.

This looses bonds, and can make a solid object into a fluid (liquid or

gas).

Nearly all substances increase in volume when they get hotter.

Metal will expand when it gets hot.

When heated, ice will melt. A solid will become a liquid.

When we heat a liquid it will

turn into a gas. We see this when we boil

water. We see steam appear. Steam is water

which has turned from a

liquid to a gas.

Now take sometime to review the

vocabulary for Unit 3 with a

friend.

In our next lesson we will take a test on all the information we

have learned in Unit 3.

Good Job Today!

And remember to….

See you next time!