How Heat Is Produced 4th Grade Science

Objectives I can identify ways that heat can be produced (e.g. burning, rubbing) and properties of materials that conduct heat better than others Students will describe the movement of heat between objects.

Vocabulary Energy- is the ability to cause change or do work. Heat- the total energy of moving particles in matter. Thermal Energy- is created by moving particles that make up matter. Solar Energy- is energy created by the sun.

Vocabulary Conduction- the transfer of heat energy by one thing touching another. Conductor- a material that readily allows heat to move. Insulator- a material that limits the amount of heat that passes through it. Conduction- is the transfer of heat energy by one thing touching another. Convection Current- forms when gas or liquid transfers heat as it moves. Radiation- energy that is sent out in little bundles, and is usually transmitted as light

How can heat be produced? Heat can be produced in several ways: Solar radiation Rubbing Burning Electricity Can you think of any examples?

Why does matter have energy? All matter is tiny particles that are always moving. In a solid, particles are closely packed. They move slightly around fixed positions. In a liquid, they are close together. They flow freely past one another. In a gas, particles are very far apart. They move in all directions. Particles in an object move because they have energy.

Measuring Moving Particles Temperature is measured with a thermometer. Most thermometers are thin glass tubes that are joined to a bulb that holds colored alcohol. If a thermometer touches matter with particles that are speeding up, particles in the liquid inside the thermometer speed up too. They move farther apart. Because the liquid expands more than the glass tube, it moves up the tube. The reading on the number line shows a greater number of degrees. If the particles slow down, the liquid contracts. The shorter column in the tube shows fewer degrees. The thermometer must be on or in whatever it’s measuring.

Heat and Temperature When a material has a high temperature, its particles move fast. The difference between heat and temperature is that temperature is the measure of particles of matter. Temperature is the measure of the average amount of motion of particles in matter. It measures the average energy. Thermal energy is the total energy of those moving particles. It measures both how fast the particles move and how many are moving. Heat is the transfer of thermal energy from one piece of matter to another.

Heat Transfer How does the energy move from a hotter to a colder object? Three mechanisms Conduction Convection Radiation

Conduction

Conduction Stir your hot soup with a metal spoon Pretty soon you need a pot holder because the end of the spoon you are holding gets hot This is heat transfer by conduction Energy travels up the spoon from the end in the hot soup to the end in your hand

Conduction We sense the movement of energy by the increasing temperature This means the atoms and molecules have higher average kinetic energy Primarily occurs by the movement of electrons in the material The more easily the electrons can move, the better the conduction

Conduction Air is a poor thermal conductor If you stand in the sun on a cold winter day and are shielded from the wind, you stay pretty warm Snow is a poor conductor, while water is better Makes igloos a useful as a house

Convection

Convection When the radiator heats the air, it becomes less dense and rises Cool air moves in to replace the air that rose This generates the air flow So radiators don’t need a fan to stir the air and to distribute heat throughout a room The rising air cools until its density matches that of the surrounding air

Convection Explains why breezes come from the ocean in the day and from the land at night

Radiation Energy carried by electromagnetic waves Study waves later in detail Light, microwaves, radio waves, x-rays Wavelength is related to vibration frequency

Radiation Interior of a car on a sunny day Sunlight comes in as visible light Seats and interior are much cooler so they radiate in the infrared instead of visible Glass in the windows blocks infrared so energy can’t get out Car interior heats up!

Lets Review There are several ways to create heat. Can you name them? Heat is a form of energy.

Ticket Out the Door Name how heat is produced. What happens to the motion of particles when an object becomes hotter?