C Heat and Temperature

Question 1

What is heat?

Answer 1

• energy, not a substance
• heat energy travels from matter at higher temperatures to matter at lower temperatures

heat is a term used to mean the energy that is transferring between substances and implies that the energy is transferred

use kinetic energy instead if you want to talk about the general movement of particles within a substance

Question 2

What is the official unit of heat energy?

Answer 2

joule (J)

Question 3

What are examples of heat related technologies?

Answer 3

• forced-air heating
• electric heaters
• air conditioners
• fire
• central heating
• chimneys
• cast-iron stoves

rough sequence of heating technology inventions:
fire –> central heating but not with coal –> chimneys –> fireplaces in walls –> cast-iron stoves –> central heating with coal –> forced-air heating –> electric heaters

Question 4

sustainable

Answer 4

something can be maintained or continued

Question 5

states of matter

Answer 5

• solid
• liquid
• gas

Question 6

melting point

Answer 6

the temperature at which the matter changes from solid to liquid

Question 7

boiling point

Answer 7

temperature at which matter changes from liquid to gas

Question 8

particle model of matter

Answer 8

a) all matter is made up of TINY particles
b) the particles are always MOVING
c) adding heat makes the particles move FASTER
d) there is SPACE between the particles

Question 9

kinetic energy

Answer 9

energy of movement

(not to be confused with heat, which is energy that is moving from hot to cold)

Question 10

compare different states of matter

Answer 10

• solid has least amount of particle movement, gas has the most
• solids have particles that are attached to each other in all directions so can only vibrate but not travel
• liquids have loose attractions between particles
• gases have no set shape and particles are not connected
• solids and liquids have definite volume (vs. gases fill the container and change density)

Question 11

temperature

Answer 11

how hot or cold matter is measured on a scale (such as degrees Celcius)

Question 12

thermal energy

Answer 12

sum of all kinetic energy that the substance contains, so if you have more of the substance at the same temperature, the thermal energy will be higher

Question 13

thermal energy

Answer 13

sum of all kinetic energy in a substance

this means that more of the substance at the same temperature makes more thermal energy

Question 14

thermal expansion

Answer 14

when a substance takes up more space because of an increase in thermal energy

Question 15

What happens when the thermal energy of a solid decreases?

Answer 15

• solid contracts
• volume decreases

Question 16

methods of heat transfer

Answer 16

• conduction
• convection
• radiation

Question 17

conduction

Answer 17

• transfer of heat energy between substances that are in contact with each other

Question 18

conductor

Answer 18

• material that allows easy transfer of heat
• metals are good conductors

Question 19

insulator

Answer 19

material that does not allow easy transfer of heat

• styrofoam is a good insulator

Question 20

convection currents

Answer 20

• hot matter rises because it is less dense than cold matter of the same type
• this causes a vacuum underneath the hot matter that is rising so substance will come in from the sides to fill the space
• if you heat something from below (such as sun heating the ground or a pot of water on the stove being heated by the element) then a current will occur since the matter is being heated more lower down and that will push up starting the current
• convection currents happen in liquids and gases such as air or water

Question 21

radiation

Answer 21

• does not require movement of particles to transfer energy
• radiant energy is transfered with invisible waves

Question 22

infrared waves

Answer 22

• the method of energy transfer for radiant energy

Question 23

good reflectors of radiant energy

Answer 23

• light colours or white
• shiny

Question 24

Natural sources of thermal energy

Answer 24

• sun
• geothermal energy (center of the Earth)
• fires
• decay

Question 25

passive vs. active heating system

Answer 25

• passive means to reduce heat loss and let the building have lots of windows facing south
• active is using technology to pump hot into colder places or to light a fire and then direct the heat towards something cold

Question 26

three components of active solar heating

Answer 26

• collector
• heat storage unit
• heat distribution system

Question 27

thermostat

Answer 27

• maintains the heat at a consistent temperature

Question 28

local heating system

Answer 28

• provides heat for only one room

Question 29

central heating system

Answer 29

heat transfers through pipes, ducts, or vents or openings to other places around the building

e.g. forced-air heating or hot-water heating are two different examples

Question 30

refrigerant

Answer 30

• evaporates at a very low temperature creating freezing temperatures inside the refrigerator
• evaporation is a process that absorbs heat so when the refrigerant evaporates, that heat is taken with it

Question 31

thermal conductivity

Answer 31

the ability to transfer heat by conduction

Question 32

alternatives for thermal energy (instead of burning fossil fuels)

Answer 32

• wind energy
• nuclear energy
• hydro-electric power

Question 33

cogeneration

Answer 33

• the production of two forms of energy at the same time from one energy source

electricity and heat could be generated together and is common