Brainscape's Knowledge GenomeTM

Browse over 1 million classes created by top students, professors, publishers, and experts.


See full index

Physics year nine > Heat > Flashcards

Heat Flashcards

You may prefer our related Brainscape-certified flashcards:
Physics 101 flashcards AP® Physics flashcards
1
Q

What is heat?

A

Heat is a form of energy. When a material is heated it gains energy and its particles move faster, therefore heat energy is seen in movement of particles

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

What is heat measured in?

A

Joules

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

What is temperature?

A

How hot or cold an object is.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

How is heat related to temperature?

A

Heat is the energy needed to raise the temperature of an object or the energy lost when an object cools down.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

What is temperature measured in?

A

Celsius (ºC) or Kelvin (K)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

What has more thermal energy and why?
Cup of tea at 80oC or swimming pool at 30oC

A

Swimming pool - it has more water molecules so stores more thermal energy.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

What are the 3 forms of heat transer?

A

Conduction
Convection
Radiation

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

What is conduction?

A

Transfer of heat energy through matter from places of higher temperature to places of lower temperature, without the movement of the matter

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

What is convection?

A

Flow of heat through a fluid (liquid or gas) from places of higher temperature to places of lower temperature by movement of the fluid itself.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

What is radiation?

A

Transfer of heat energy from a place of higher temperature to a place of lower temperature by means of electromagnetic waves.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

How does conduction work?

A

When something is heated it’s particles gain thermal energy causing them to vibrate more vigorously.
The particles bump in to nearby particles making them vibrate as well.
This passes the thermal energy through the object by conduction from the hot to the cold end.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

Why is metal a very good conductor of heat?

A

Metals have many free electrons. These free electrons can travel through the metal transferring the heat more quickly.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

How does convection work?

A

Convection happens due to hot liquid/hot gas expanding making it less dense.
Less dense liquid/gas rises causing convection currents.
These convection currents transport the energy.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

How does radiation work?

A

Doesn’t need a medium i.e. can travel through a vacuum
Transfers at speed of light in straight lines
Every object which is at a temperature above it’s surroundings loses heat through radiation even people.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

By what method does the heat from sun reach earth

A

Radiation as space is a vacuum i.e. it is empty and has not particles in it.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

Where is most heat lost in a home

A

Walls

17
Q

What percentage of heat is lost through the roof?

A

25

18
Q

What can be used to reduce heat loss through the roof?

A

Loft Insulation - fibreglass ‘wool’ laid across the loft floor
Reduced conduction through ceiling into loft
Cost: 450, Annual Saving: 150

19
Q

What percentage of heat is lost through walls?

A

35

20
Q

What can be used to reduce heat loss through walls?

A

Cavity wall Insulation
Cavity wall -Two layers for brick with a gap between them reduce conduction
Insulation - Foam squirted into the gap trapping pockets of air to minimise convection
Cost: 500, Annual Saving: 100

21
Q

What percentage of heat is lost through draughts?

A

15

22
Q

What can be used to reduce heat loss through draughts?

A

Draught proofing - strips of foam and plastic around doors and windows stop air going out reducing convection.
Cost: 30, Annual Saving: 20

23
Q

What percentage of heat is lost through floors?

A

10

24
Q

What can be used to reduce heat loss through floors?

A

Carpet - reduce conduction
Cost: 400, Annual Saving: 40

25
Q

What percentage of heat is lost through windows?

A

15

26
Q

What can be used to reduce heat loss through windows?

A

Double glazing- two layers of glass with an air gap between reduces conduction
Cost: 3000, Annual Saving: 100
Thick curtains - reduces conduction and radiation through windows
Cost: 180, Annual Saving: 20

27
Q

What can be used to reduce heat loss through the hot water tank?

A

Lagging such as fibre glass wool reduces conduction
Cost: 20, Annual Saving: 40

28
Q

How do you calculate payback time (in years)

A

Payback time = cost/savings per year

Physics year nine (3 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2024 Bold Learning Solutions. Terms and Conditions