Topic 1 - Heat

Question 1

What is the structure of gas?

Answer 1

Well separated, no regular pattern

Question 2

What is the structure of a liquid?

Answer 2

Close together, no regular pattern

Question 3

What is the structure of a solid?

Answer 3

tightly packed, usually in a regular pattern

Question 4

What is the movement of a gas?

Answer 4

Vibrates and moves freely at high speed

Question 5

What is the movement of a liquid?

Answer 5

Vibrates, moves about and slides past each other

Question 6

What is the movement of a solid?

Answer 6

Vibrates, generally doesn’t move from place to place

Question 7

What is a thermal insulator? (give an example and an everyday example)

Answer 7

Something that prevents heat from moving from place to an another
E.g. Feathers and wood
Clothing and bedding

Question 8

What is a thermal conductor? (give an example and an everyday example)

Answer 8

A material that transfers thermal energy well.
E.g. Aluminium, Copper
Saucepan, Radiator

Question 9

What is expansion?

Answer 9

When a solid is heated the atoms begin to vibrate more. When this happens the atoms take up more space and the size of the material increases: it expands.

Question 10

Explain how expansion takes place on railway tracks and why it is important?

Answer 10

Small gaps (called expansion gaps) are left between rails as the there is an expansion of the rails in hot weather

Question 11

What is conduction and how does it work?

Answer 11

The thermal transfer of energy between neighbouring atoms. When atoms gain energy, they begin to vibrate more. When one atom collides with another, some of this energy is transferred.

Question 12

Can conduction takes place in a vacuum? e.g. space

Answer 12

No, conduction can only take place where there is particles and the there are no particles in vacuum such as space.

Question 13

What is radiation?

Answer 13

Heat transfer due to infra-red radiation

Question 14

What surfaces are good absorbers and emitters of infra-red radiation?

Answer 14

Dark, matt surfaces

Question 15

What surfaces are poor absorbers and emitters of infra-red radiation?

Answer 15

Light, shiny surfaces

Question 16

Explain why convection cannot take place in solids

Answer 16

Convection cannot take place in solids because thr particles are not free to move

Question 17

Describe the process of convection

Answer 17

1. A fluid is heated. The temperature of the fluid increases and the particles begin to vibrate more.
2. The particles move further apart. This reduces the density of the fluid.
3. The warmer fluid begins to rise as it is less dense than the surrounding fluid.
4. It is replaced by colder fluid moving underneath, which is then also heated.
5. The warmer fluid at the top begins to cool, its density increases and it begins to sink.

This creates a cycle thar repeats.

Question 18

Identify where conduction convection and thermal transfer by radiation are taking place

Answer 18

Conduction usually occurs in solids
Convection occurs fluids (liquids and gases)
Radiation occurs in a vacuum like space