7C: Heat & Temperature

Question 1

It is a hot day and your family decides to have ice cream with dinner. You walk the 30 min to the store to get 1 L of ice cream. Knowing that it will melt before you get back, you need to make a plan to get the ice cream home in its solid state. What would you do? Why?

Answer 1

Answers will vary.

Question 2

What does the word sustainable mean?

Answer 2

Sustainable means that something can remain the same, maintained or continued for a long period of time/forever.

Question 3

What is heat energy and how is it measured?

Answer 3

Energy that flows from matter to a higher temperature to matter at a lower temperature.

• It is measured in Joules (J).

Question 4

What is particle model of matter?

Answer 4

Model that explains the behavior of solids, liquids, and gases.

Question 5

What are the 4 main points of the particle model of matter?

Answer 5

1. All matter is made up of tiny particles
2. These particles are always moving
3. The particles have space between them
4. Adding heat causes the particles to move faster

Question 6

List what happens when a gas heats up, or when it gets cooled off.

Answer 6

When the gas is heated, its particles speed up. When it is cooled, its particles slow down.

Question 7

What is kinetic energy?

Answer 7

The energy of movement; particles that make up matter have kinetic energy because they are always moving.

Question 8

What is volume?

Answer 8

Volume refers to the amount of space occupied by matter; milliliters(mL) and liters (L) are common units of volume.

-Volume can also be measured in cm, feet, etc.

Question 9

What is thermal energy?

Answer 9

Total kinetic energy of the particles in a substance. The faster the particles are moving, the more kinetic energy is present.

Question 10

What is temperature?

Answer 10

A measurement how hot or cold matter is.

Question 11

What is the difference between heat, temperature, kinetic energy and thermal energy?

Answer 11

Heat: the energy that transfers from one substance to another because of differences in kinetic energy.

Temperature: measurement of how hot or cold matter is.

Kinetic Energy: the energy of movement (usually particles)

Thermal Energy: Total kinetic energy of an object/matter.

Question 12

What are two specific ways that matter can change its volume when heated or cooled?

Answer 12

Expansion & Contraction

Question 13

What is expansion?

Answer 13

An increase in volume; matter expands when heat energy is added.

Question 14

What is contraction?

Answer 14

The decrease in volume; matter contracts when the heat energy is removed.

Question 15

When water is frozen, does it expand or does it get smaller?

Answer 15

Water is unique because it expands when it is frozen/cooled.

Question 16

Explain what has happened: A large area of concrete is poured as a single slab to create a new outdoor basketball court for our school. The work is done in August before the new school year starts. A very cold winter follows. When spring comes and you and your friends want to use the court, younotice several large cracks in the concrete. It looks like the concrete will need replacing.

Answer 16

The concrete has cracked due to the forces applied during expansion during the spring/summer, and contraction during the winter months. Since concrete is a solid it has a fixed volume and does not react well to changes in kinetic energy.

Question 17

Explain what has happened: You are working on your bike on a hot summer afternoon. You need to replace a metal bolt, and you find that it fits inside a metal nut. Leaving most of your tools and the bike sitting in the sun, you take a break for an hour. When you come back, you pick up the bolt and find that it’s hot to the touch. You grab the right size of metal nut that has been sitting in the shade. It doesn’t fit. You use an identical nut that had been sitting in the sun, and it fits.

Answer 17

The sun has caused the metal to expand.

When the metal was in the shade it stayed the same/contracted slightly.

***Welders will use this principle to adjust the gaps between pieces of metal. If the gap is slighlty too large they will heat up the metal to cause it to expand and close the gap off.

Question 18

Train tracks span great distances. Spaced many metres apart are small gaps between the rails. What might happen if the gaps weren’t there?

Answer 18

If they gaps were absent, then any time it was hot outside and the metal expanded the traintracks would probably malfunction, bend/warm, or be dangerous.

Question 19

Explain what has happened: After getting caught in a summer thunderstorm, you decide to make yourself a mug of hot chocolate. The biggest mugs are in your kitchen freezer, chilled and ready for lemonade on the next hot day. You take one, noticing that the thick glass is covered with a light layer of frost. As you pour the boiling water into the mug, you hear and see it crack.

Answer 19

The extremely high temperature of the water caused the frozen mug to crack because it applied too much heat too quickly. The rapid change in kinetic energy of the particles caused the mug to break.

Question 20

What is thermal expansion?

Answer 20

The expansion of a substance caused by an increase in thermal energy, causing the particles to move faster and farther apart..

Question 21

What are the three methods of heat transfer?

Answer 21

1. Conduction
2. Convection
3. Radiation

Question 22

True or False? All 3 methods of heat transfer (conduction, convection, and radiation), rely on the movement of particles.

Answer 22

False. Both conduction and convection rely on the movement of particles to transfer heat energy. Radiation does not.

Question 23

What is conduction? Can you provide an example?

Answer 23

The flow of energy between substances that are in contact.

Ex:

• Metal spoon gets hot while sitting in hot soup
• Water boils in pot because the metal pot is being heated by the flame/burner below.

Question 24

In regards to conduction, what is the only way that heat can transfer?

Answer 24

From an area of greater kinetic energy, to an area of lower kinetic energy.

Question 25

What are conductors?

Answer 25

Any material that allows heat energy or electricity to flow easily. Conductors are usually solids such as metals. There are some liquids and even fewer gases that are good conductors of heat.

Question 26

List three materials that conduct energy.

Answer 26

Water, Copper, Wires.

Question 27

What are insulators?

Answer 27

Any material that does not allow heat energy or electricity to flow easily.

Plastic, cork, and wood are good insulators because they reduce the amount of heat that can transfer from a hotter object to a colder one.

Question 28

What are convection currents?

Answer 28

The pattern of moving liquid or gas particles when heat energy is transferred to a substance.

Hot fluids are less dense and rise, while colder fluids are more dense and sink.

Question 29

What is radiation?

Answer 29

Radiation is the transfer of energy by invisible waves that can travel great distances. Energy transferred from its source by radiation is called radiant energy.

Question 30

What are infrared waves?

Answer 30

Invsible waves of radiant energy that transfer heat energy.

Question 31

Explain what types of objects would reflect/absorb radiant energy.

Answer 31

Shiny and light coloured are good reflectors of radiant energy.

Dark and dull objects are good at absorbing radiant energy.

Question 32

What are two types of solar heating systems?

Answer 32

Passive & Active

Question 33

Explain the difference between passive and active solar heating.

Answer 33

Passive Heating: is when a solar-system is heated directly by the sun.

Active Heating Systems: rely on some mechanical devices to help transfer that energy.

Question 34

What are 3 components of Active Solar Heating Systems?

Answer 34

• a collector
• a heat storage unit
• a heat distribution system

Question 35

What is a solar array?

Answer 35

The arrangement of solar cells in panels that are connected, and then positioned to capture and store the sun’s energy in low-voltage batteries

Question 36

What is a local heating system?

What are some common examples of local heating systems?

Answer 36

A method of providing thermal energy for one small area specifically.

• Fireplaces, wood-burning stoves, and space

heaters are common examples of local heating systems.

Question 37

What are central heating systems? What are some examples?

Answer 37

A method of transferring thermal energy from a single, central source through a network of pipes, ducts, and vents.

Ex: furnaces, forced air heating, hot water tanks,

Question 38

What is the difference between forced air heating and hot water heating?

Answer 38

Convection plays a large role in each of these heating systems. See the attached image for more detail.

Question 39

Where does heat loss occur in the average housing structure?

Answer 39

See the attached image.

Question 40

Define R-Value.

Answer 40

R-Value is the number that indicates the ability of an insulating material to stop the heat energy from transferring.

The higher the R-Value, the better the product is at insulating.

Question 41

What is the difference between renewable and non renewable natrual resources?

Answer 41

Natural resources come from the environment.

Renewable resources can easily be replaced/reused such as wind or the sun.

Non-renewable resources are limited resources that cannot be replaced such as coal, gold, fossil fuels, etc.

Question 42

What is cogeneration?

Answer 42

Cogeneration is the production of two forms of energy (usually electricity and heat) at the same time from one energy source.