3 - Heat Flashcards

You may prefer our related Brainscape-certified flashcards:
1
Q

Which colour emits and absorbs heat best?

A

(Matte) Black

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

Which colour emits and absorbs heat worst?

A

Silver (Foil)

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

Which of these transfers energy better?:
a) a sourcepan on a hob with boiling water
b) boiling water inside a sealed flask

A

A - The heat energy is transferred out of the saucepan and into the air
The thermos flask is a closed system as no energy can escape

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

What types of energy transfers are used when heating objects?

A

Heating - energy transferred from hotter to colder objects
Radiation - energy transferred by waves (eg sun rays -> earth)

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

What do particles do when an object is heated?

A

The particles in the hotter part vibrate more & collide with each other, transferring heat energy to other particles

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

What is conduction?

A

The transfer of energy from an object’s stores to another object’s energy stores, making their particles vibrate faster

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

What is thermal conductivity?

A

How well an object transfers energy by conduction

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

What materials have a high thermal conductivity?

A

Metals - Heat transfers through the particles in a metal quickly

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

What materials have a low thermal conductivity?

A

Gases (eg air)

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

Why do houses need walls with a low thermal conductivity?

A

As it’s good to have a slow rate of energy transfers through them

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

What else keeps houses warm?

A

Thick walls - the thicker the wall, the slower the rate of energy transfer

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

What else stops a house losing heat energy?

A

Using thermal insulators (objects made from materials that don’t transfer heat well)

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

How do double glazing or cavity walls in a house work?

A

There is an inside wall and an outside wall and an air gap in between
The air gap is not a good conductor of energy so this reduces the amount of energy transferred by conduction through the walls

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

Why is fibre glass wool used in the loft or around water tanks?

A

It’s thick so reduces the rate of energy transfer through the ceiling into the loft space

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

What is convection?

A

The transfer of heat through liquids

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

What happens to particles in convection?

A
  • The water is heated, giving the particles more energy and they move faster
  • The increased particle speed causes the particles to tae up more space
  • The liquid expands and rises upwards
17
Q

What are some examples of convection?

A
  • Cooking in a saucepan
  • Radiators
  • Lava lamps
  • Weather
18
Q

What is thermal radiation?

A
  • Heat emitted by our own bodies or the sun by infrared rays (we can see this through an infrared camera)
  • The heat the gets absorbed by objects
19
Q

How do our bodies keep at a constant temperature?

A

It needs to radiate the same average heat it absorbs