# 07. P2 Energy Transfer by Heating Flashcards

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1
Q

What state of matter does conduction occur in?

A

Solid

2
Q

What property describes how rapidly heat moves through a solid?

A

Thermal Conductivity

3
Q

Explain why birds fluff up their feathers in winter.

A

Fluffing feathers traps air, air is a good insulator so less energy is as lost through conduction.

4
Q

A metal and a wooden pole have been out all night on a frosty evening, in the morning you pick one up with your left hand and one with your right. Which one feels coldest and why?

A

Metal feels coldest as it is a good conductor so conducts more energy away from your hand each second. So feels colder, but BOTH are actually at the same temperature.

5
Q

Explain why a mug of cappucino with milk froth on the top, cool down slower than an plain cup of tea.

A

Frothy milk has air trapped in it. Air is a good insulator so reduces heat loss by conduction.

6
Q

What is the name given to a poor conductor?

A

Insulator

7
Q

State the name given to thermal energy transfer in the form of a wave?

A

8
Q

How does the temperature of the object affect the amount of IR radiation given out?

A

Hotter = more radiation given out per second

9
Q

What objects are the best emitters of IR radiation?

A

Black and Matt objects

10
Q

What objects are the best absorbers of IR radiation?

A

Black and Matt objects

11
Q

Which objects are the best reflectors of IR radiation?

A

White and shiny

12
Q

If you pour a freshly boiled cup of tea. Explain why it cools down at a quicker rate just after it has been freshly boiled rather than 5 minutes later.

A

The temperature difference between the room and the cup of tea is at its greatest immediately after pouring it.

13
Q

PHYSICS ONLY - State the three main types of greenhouse gases?

A

Methane, Carbon Dioxide, and Water vapour

14
Q

PHYSICS ONLY - State the difference between IR rays given off by the Sun and the Earth?

A

IR rays from the Sun has a shorter wavelength

15
Q

PHYSICS ONLY - Explain how the presence of greenhouse gases keep the Earth warm.

A

Some of the IR rays emitted from the Earth are absorbed by the greenhouse gases, and then emitted out in all directions with some of them going back towards the Earth.

16
Q

PHYSICS ONLY - Explain the effect of an increasing amount of greenhouse gases present in the atmosphere on the Earth.

A

Global warming - leading to issues such as polar ice caps melting, flooding to low lying land, destruction of habitats etc.

17
Q

List the different places heat is lost from a house.

A

Roof, Walls, floor, windows, Draughts

18
Q

State what can be added to a house to reduce heat loss through the house?

A

Loft insulation

19
Q

State what can be added to a house to reduce heat loss through the walls?

A

Cavity wall insulation

20
Q

State two things which can be added to a house to reduce heat loss through windows?

A

Double glazing and curtains

21
Q

Describe how loft insulation reduces heat loss through the roof.

A

Loft insulation has air pockets trapped in it. Air is a good insulator so reduces heat loss by conduction

22
Q

Describe how cavity wall insulation reduces heat loss through the roof.

A

Cavity wall insulation has air pockets trapped in it. Air is a good insulator so reduces heat loss by conduction

23
Q

How does a sheet of aluminium foil between a radiatior panel and wall help reduce energy losses?

A

Radiation from the radiator is reflected away from the wall and so reduces the rate of energy transfer into the wall by radiation

24
Q

How do double glazed windows help to reduce energy losses?

A

The air gap between the two panes of glass reduces heat loss by conduction, as air is a good insulator.

25
Q

The energy transfer per second through a layer of insulating material depends on what three factors?

A

1) Temperature difference, 2) material thickness, 3)thermal conductivity of the material

26
Q

What happens to the temperature of an object that absorbs more IR radiation than it emits?

A

The temperature increases

27
Q

What is the name given to a type of body that does not reflect or transmit any radiation?

A

A black body object

28
Q

What is the name given to the best possible emitter of infrared radiation?

A

A black body object

29
Q

Why do rescue teams use light-coloured shiny blankets when treating someone?

A

To keep people warm - light, shiny surfaces reflect the heat emitted from the body back to the person, and also emit less radiation than if it was a dark, matt surface

30
Q

What factors determine the rate of thermal energy transfer?

A

Temperature Difference, Thickness of Material, Thermal Conductivity of material.