Thermal Energy

Thermal Energy

feat. Temperature & Heat

Movement = Heat

Do you remember the Kinetic Theory of Matter? This states that the particles that make up matter are constantly in motion. Because those particles are in motion, they have kinetic energy. The faster they move, the more kinetic energy they have. The more kinetic energy the particles of a substance have, the "hotter" it feels.

Thermal Energy

An object's thermal energy is dependent on its temperature and mass. The higher the temperature of a substance, the more thermal energy it has. At the same temperature, a higher mass of a substance will contain more thermal energy.

Multiple Choice

Which of the following is NOT a part of the Kinetic Theory of Matter?

• All matter is made up of tiny particles.

• Particles are always moving in random paths

• Occasionally, particles stop moving.

• The type of movement of particles depends on the amount of energy.

Multiple Choice

When the temperature of matter decreases the particles ...

• speed up and move farther apart

• slow down and move farther apart

• speed up and move closer together

• slow down and move closer together

Multiple Choice

There are four cups of hot cocoa. The cup sizes are shown. The temperature of the cocoa in each cup is 25 ^oC. Which cup has the MOST thermal energy?

• Large cup (Trenta)
• Small cup (Tall)
• Venti
• All three are the same temperature so they have same thermal energy

Multiple Choice

When thermal energy is added to a substance, the substance's particles move:

• More rapidly at an increased diestance from each other.
• More rapidly with less distance between each other.
• More slowly with a greater distance between each other.
• More slowly with a reduced distance between each other.

Multiple Choice

Which phase change occurs between points D and E if heat is added?

• boiling

• freezing

• melting

• condensing

Temperature

Temperature is a measure of the average kinetic energy of all of the particles in an object. If the particles in a solid are vibrating very fast, it would have a high average kinetic energy or temperature. Objects at a low temperature have particles that have less average kinetic energy.

Temperature

There are 3 commonly used temperature scales. The Fahrenheit scale is used in the US. The Celsius scale is most commonly used in the rest of world and by scientists. The Kelvin scale is mainly used by physicists who deal with extreme temperatures.

Multiple Choice

___________________ is the measure of the average kinetic energy of particles of a substance.

• A thermometer

• Expansion

• Farenheit

• Temperature

Multiple Choice

Water freezes at 32 degrees on which scale?

• Farenheit
• Celsius
• Kelvin

Multiple Choice

Water boils at 212 degrees on which scale?

• Farenheit
• Celsius
• Kelvin

Multiple Choice

Water boils at 100 degrees on which scale?

• Farenheit
• Celsius
• Kelvin

Multiple Choice

Energy is transferred as heat between two objects of ___________ temperatures. 

• differing
• same

Heat

Heat is defined as the energy transferred from an object at a higher temperature to an object at lower temperature. When two objects come into contact, energy is always transferred in this way. When you put an ice cube into a glass of water heat is transferred from the warmer water to the colder ice cube. 

Heat can be transferred from one object to another in three ways...

Conduction

This is the transfer of energy from direct contact. When objects at different temperatures come into contact, the warmer object transfers it energy to the cooler object. This energy transfer will continue until both objects get to the same temperature or the objects are no longer in direct contact.

Conduction

Conduction can also occur within the same object where heat is transferred from the warmer to the cooler part of the object, like what happens when you put a metal spoon into a hot cup of coffee.

Conductors & Insulators

Some materials can transfer heat better than others. A conductor is a substance that transfers heat well. Examples are metals like iron and nickel. Substances that are not good at transferring heat are called insulators. Examples would be air, plastic and fabrics.

Convection

Energy in the form of heat can also be transferred through the movements of fluids. Convection occurs when a cooler particles replace warmer particles by pushing them upward. When you boil water in a pot, the warmer water moves in roughly circular patterns because of convection and this motion is referred to as a convection current.

Radiation

This is the transfer of energy by electromagnetic waves. When radiation is emitted from one object and then absorbed by another, the result is often a transfer of heat. Unlike conduction and convection, radiation can travel through empty space as it does when the sun's energy reaches the Earth from 93 million miles away.

Multiple Choice

In nature, heat always flows from a:

• cold object to a warm object.
• small object to a big object.
• warm object to a cold object.
• large object to a small object.

Multiple Choice

Heat transfer by conduction occurs when...

• particles bump into each other
• large numbers of atoms move from place to place
• atoms give off heat in the form of electromagnetic waves
• electromagnetic waves travel from place to place through a vacuum

Multiple Choice

List the correct order of conduction.
1. They collide more vigorously with neighbouring particles
2. Particles at the heated end gain kinetic energy and vibrate vigorously.
3. Particles at cooler end vibrate vigorously.

• 1, 2, 3
• 3, 2, 1
• 2, 1, 3
• 1, 3, 2

Multiple Choice

Which material is the best conductor of heat?

• Wood
• Plastic
• Glass
• Steel

Multiple Choice

Why are gases poor conductors of heat?

• Particles are close together and collisions are more frequent

• Particles are far apart and collisions are less frequent

• Particles are close together and collisions are less frequent

• Particles are far apart and collisions are more frequent

Multiple Choice

Convection can take place in ____________.

• solids only.

• liquids only.

• liguids and gases only.

• solids, liquids and gases.

Multiple Choice

When air is heated, its density ___________.

• increases

• decreases

• remains the same

Multiple Choice

When air is heated, its volume ____________.

• increases

• decreases

• remains the same

Multiple Choice

What thermal energy transfer causes your skin to feel warm when it is in the sun on a summer day?

• Conduction

• Convection

• Radiation

• Evaporation

Multiple Choice

A crayon placed on a dark driveway in bright sunlight melted into a colorful puddle. What caused the crayon to melt?

• Solar radiation heated the driveway and then heat transferred to the crayon by conduction.

• Solar radiation heated the driveway and then heat transferred to the crayon by radiation.

• Solar convection heated the driveway and then heat transferred to the crayon by radiation.

• Solar convection heated the driveway and then heat transferred to the crayon by conduction.

Poll

How do you feel about thermal energy?

• I'm so hot, I want all the smoke...

• I'm cooler than cool

• I'm freezing like a polar bear's toenails!

• I know absolute zero about this