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Flashcards in Heat Deck (70)
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0
Q

Heat can cause ___________. For example ____________.

A

A steam engine

1
Q

What is heat?

A

heat is a form of energy

2
Q

What is heat measured in?

A

joules

3
Q

what is temperature measured in?

A

degrees celsius

4
Q

What happens to materials when heated?

A

They expand

5
Q

What happens materials when cooled?

A

They contract

6
Q

at what temperature does water behave like other liquids?

A

Above 4 degrees celsius

7
Q

what happens to water above 4 degrees celsius?

A

It behaves like other liquids

8
Q

What happens to water below 4 degrees

A

behaves oppositely to other liquids

9
Q

At what temperature does water behave oppositely to other liquids?

A

below 4 degrees

10
Q

what does reducing pressure do to water?

A

It lowers it’s boiling point below 100 degrees celsius

11
Q

What does increasing pressure do to water?

A

It raises it’s boiling point above 100 degrees

12
Q

What is temperature?

A

the measure of how hot or how cold something is

13
Q

What is latent heat?

A

when heat causes a change in state and not a change in temperature

14
Q

What is latent heat of fusion?

A

When heat changes a solid to a liquid with no temperature change.

15
Q

What is latent heat of vaporisation?

A

when heat changes a liquid to a gas with no change in temperature

16
Q

what are the three methods heat can travel by?

A

conduction, convection and radiation

17
Q

What are insulators?

A

Materials that are poor conductors of heat

18
Q

In general metals are __________________.

A

good conductors of heat

19
Q

What happens to solids liquids and gases when…

(i) heated
(ii) cooled

A

(i) they expand

(ii) they contract

20
Q

In what way does heat always move?

A

From something hot to something colder.

21
Q

What is conduction?

A

conduction is the movement of heat through a solid without the particles in the solid moving out of position.

22
Q

Metals are ____________. what does this mean?

A

conductors of heat. Heat passes through them easily by conduction.

23
Q

name a good conductor

A

metals

24
Q

What is an insulator?

A

a substance that does not allow heat to pass through it easily.

25
Q

Insulators are…

A

poor conductors

26
Q

Name two insulators.

A

wood and plastic

27
Q

why are insulators used in the home?

Name 5 examples of this

A

to prevent heat loss

air trapped between two pains of glass in double glazed windows, feathers are used in bedding, fibreglass is used in attics to prevent heat loss, the material in a lagging jacket prevents heat loss from the hot water cylinder and polystyrene put between cavity walls in houses.

28
Q

What is convection?

A

convection is the movement of heat through a liquid or gas by the movement of the particles in that liquid or gas.

29
Q

What is radiation?

A

the movement of waves that can travel through a vacuum.

30
Q

what is a vacuum? give an example

A

where there are no particles at all e.g. space

31
Q

what is the difference in heat movement between a dull, black surface and a bright, shiny surface.

A

a dull, black surface radiates out heat better than a bright, shiny surface. a dull, black surface absorbs heats better than a bright, shiny surface.

32
Q

what is latent heat?

A

the heat used by a substance to change it’s state - it does not raise the temperature.

33
Q

What is the difference between heat and temperature.

A

heat is a form of energy, temperature is a measure of how hot or how cold something is. heat is measured in joules. temperature is measured in degrees celsius.

34
Q

As heat is a ______________ it can be ________________.

A

As heat is a form of energy it can be converted into other forms

35
Q

What do most materials do when heated?

Give an example

A

expand

Gaps are left in railway tracks to prevent the tracks from buckling when they expand in hot weather.

36
Q

What do most materials do when cooled?

Give an example

A

contract

high voltage cables contract when cooled the cables are slack to avoid snapping in winter

37
Q

Not all solids, liquids and gases expand by…

A

The same amount

38
Q

what is the basic scientific principle behind the bi-metallic strip?

A

the fact that different solids expand by different amounts.

39
Q

Name a use of the bi-metallic strip

A

switching on and off electrical circuits in response to a temperature change.

40
Q

What happens when the bi-metallic strip is heated?

A

the copper expands more than the iron. this causes the bi-metallic strip to bend.

41
Q

what will happen when the bi-metallic strip is cooled?

A

It will return to it’s original shape.

42
Q

What is the special temperature for water?

A

4 degrees celsius

43
Q

What will happen to water if you heat it above 4 degrees celsius

A

It will expand

44
Q

What will happen to water if you cool it below 4 degrees celsius

A

It will expand

45
Q

Above 4 degrees water…

A

behaves like any other liquids

46
Q

below 4 degrees water…

A

behaves oppositely to other liquids

47
Q

The behaviour of water makes it ________.

A

unique

48
Q

What is the difference in relation to heat between a spoonful of boiling water and a pot of boiling water.

A

the pot full has more energy but the same temperature as the spoonfull.

49
Q

Name a poor conductor and a good insulator

A

water

50
Q

Poor conductors of heat are considered to be…

A

insulators

51
Q

why are insulators important in the home?

A

to reduce heat energy losses

52
Q

Heat will travel along a metal bar by….
The heat energy is…
The heat ________________ but the atoms do not ________________. They___________.

A
Conduction
Passed from atom to atom along the bar.
Moves along the bar
Move along the bar
Vibrate
53
Q

What is happening if we heat something and the temperature does not rise?

A

It is changing state

54
Q

If you continue to lower the temperature of water below 4 degrees celsius what will happen?

A

It will continue to expand

55
Q

What happens to water at 0 degrees celsius?

A

It starts to turn into a solid called ice.

56
Q

ice is ___________ than water

A

less dense

57
Q

Because of ___________ the volume of ice is ___________ than the volume of water

A

volume

greater

58
Q

ice _________ on water

A

floats

59
Q

Name two examples where the unusual behaviour of ice has an effect on something.

A

Pipes burst in cold weather because water expands when it freezes.
When lakes freeze ice floats on top of the water because ice is less dense than water. This acts as a barrier between the cold air and the water below and allows fish to survive.

60
Q

In conduction it is as if the heat is _______________. This is like…

A

passed from atom to atom

Pass the parcel

61
Q

What does heat travel through liquids and gases by?

A

Convection

62
Q

Name two examples of convection

A

When water molecules at the bottom of a saucepan get heat from the cooker these hot molecules move. The hot molecules bring the heat with them.
When air molecules get heat from heaters in a room these hot molecules move around the room. The hot molecules bring the heat with them.

63
Q

how does heat reach the Earth from the Sun?

A

radiation

64
Q

What does radiation not require?

A

medium

65
Q

What is heat radiation considered to be?

A

electromagnetic waves

66
Q

What do all hot objects emit?

A

heat by radiation

67
Q

What is the average temperature of the human body?

A

37 degrees celsius

68
Q

What does the human body emit?

A

heat by radiation

69
Q

What can detect heat radiation?

A

special heat cameras