Topic 8 - energy resources and transfers

Question 1

Temperature?

Answer 1

Temperature - A measure of the average kinetic energy of the particles

Question 2

Absolute Zero -

Answer 2

The lowest possible temperature. This is the temperature where the particles stop moving. It is -273C.

Question 3

Thermal Energy Transfers -

Answer 3

This is where energy travels from the high temperature region to the low temperature region

Question 4

solid

Answer 4

Solids have particles which are very close together. The particles cannot move from place to place; the only way they can move is to vibrate about a fixed position.

If energy is supplied to a solid, its particles vibrate (oscillate) with a largeramplitude (side to side distance), and the solid expands*.
Eventually, the particles may gain so much energy that they partially overcome the attractive forces between them, and become free to move over each other. This is melting

Question 5

gas

Answer 5

Gases have particles which are very spread out. The particles move randomly in any direction. The spaces between the particles are much greater than in the liquid, so a substance is more less dense as a gas than as a liquid.

Heating a gas makes its particles move around more quickly, and the gas expands*.

Question 6

liquid

Answer 6

Liquids have particles which are also close together. The particles can move around, but they are still in contact with each other. The spaces between the particles are greater than in the solid, so a substance is lessdense as a liquid than as a solid.

Heating a liquid makes its particles move around more quickly, and the liquid expands*.
Eventually, the particles may gain so much kinetic energy that they overcome the remaining attractive forces between them and become free to move in any direction, This is evaporation or boiling.

Question 7

Conduction

Answer 7

Conduction is the transfer of thermal energy through a substance by collisions between particles.

Conduction is especially important in solids.

Question 8

example of conduction?

Answer 8

If you pick up a spade by its wooden handle on a cold day, it feels quite warm because the wood is a poor conductor (insulator) so the random internal energy from your hand is only conducted away slowly.

Question 9

Convection?

Answer 9

Convection is the transfer of thermal energy through a substance by the movement of particles due to changes in density. Convection is impossible in solids or in a vacuum, but it is important in liquids and gases.

Question 10

example of Convection?

Answer 10

2. Heating water in a kettle

Question 11

Radiation?

Answer 11

Thermal radiation is the transfer of thermal energy via Electromagnetic waves,(rather like visible light, but usually at a lower frequency so we can’t see it). Particles of matter are not involved, so radiation even happens in a vacuum (like Space!).

Question 12

Example of Radiation?

Answer 12

Marathon runners are given shiny, silvery aluminium blankets at the end of a race to reflect thermal radiation back towards the body.

Question 13

Speed equation?

Answer 13

v2 = u2 + 2as