Energy

Question 1

Explain kinetic energy.

Answer 1

Moving things have kinetic energy. The heavier a thing is and the faster it moves the more kinetic energy it has. All moving things have kinetic energy, even very large things, like planets, and very small ones, like atoms.

Question 2

Explain sound energy.

Answer 2

A vibrating drum and a plucked guitar string transfer energy to the air as sound. Kinetic energy from the moving air molecules transfers the sound energy to your eardrum.

Question 3

Explain thermal energy.

Answer 3

Thermal energy is what we call energy that comes from heat. A cup of hot tea has thermal energy in the form of kinetic energy from its particles. Some of this energy is transferred to the particles in cold milk, which you pour in to make the tea cooler.

Question 4

Explain chemical energy.

Answer 4

Some chemical reactions release energy. For example, when an explosive goes off, chemical energy stored in it is transferred to the surroundings as thermal energy, sound energy and kinetic energy.

Question 5

Explain electrical energy.

Answer 5

A battery transfers stored chemical energy as electrical energy in moving charges in wires. For example, electrical energy is transferred to the surroundings by the lamp as light energy and thermal energy.

Question 6

Explain gravitational potential energy.

Answer 6

A rock on a mountain has stored energy because of its position above the ground and the pull of gravity. This energy is called gravitational potential energy. This is the energy it would release if it fell. As the rock falls to the ground, the gravitational potential energy is transferred as kinetic energy.

Question 7

What do energy transfer diagrams show?

Answer 7

The locations of energy stores and energy transfers.

Question 8

What do sankey diagrams do?

Answer 8

Summarise all of the energy transfers taking place.

Question 9

What is heat?

Answer 9

The amount of thermal energy it contains.

Question 10

What is temperature?

Answer 10

How hot or cold something is.

Question 11

What is heat measured in?

Answer 11

Joules.

Question 12

What is temperature measured in?

Answer 12

°C

Question 13

How can thermal energy be transferred?

Answer 13

Conduction, convection and radiation.

Question 14

Explain conduction.

Answer 14

When a substance is heated, its particles gain energy and vibrate more vigorously. The particles bump into nearby particles and make them vibrate more. This passes the thermal energy through the substance by conduction, from the hot end to the cold end.

Question 15

Explain convection.

Answer 15

The particles in liquids and gases can move from place to place. Convection happens when particles with a lot of thermal energy in a liquid or gas move, and take the place of particles with less thermal energy. Thermal energy is transferred from hot places to cold places by convection.

Question 16

Explain radiation.

Answer 16

All objects transfer thermal energy by infrared radiation. The hotter an object is, the more infrared radiation it gives off.
No particles are involved in radiation, unlike conduction and convection. This means that thermal energy transfer by radiation can even work in space, but conduction and convection cannot.

Question 17

How is radiation different to conduction and convection?

Answer 17

Conduction and convection need moving particles to transfer energy whereas radiation does not.

Question 18

What is the difference between renewable and non-renewable energy?

Answer 18

Non-renewable energy resources cannot be replaced once they are all used up.
Renewable energy resources can be replaced, and will not run out.

Question 19

Name three fossil fuels.

Answer 19

Coal, oil and natural gas.

Question 20

Name some forms of renewable energy.

Answer 20

Biomass, wind power, water power, geothermal, solar cells, solar panels.

Question 21

Explain biomass.

Answer 21

Biomass fuels come from living things. Wood is a biomass fuel. As long as we continue to plant new trees to replace those cut down, we will always have wood to burn. Just as with the fossil fuels, the energy stored in biomass fuels came originally from the Sun.

Question 22

Explain wind power.

Answer 22

Wind is caused by huge convection currents in the Earth’s atmosphere, driven by heat energy from the Sun. The moving air has huge amounts of kinetic energy, and this can be transferred into electrical energy using wind turbines. Wind turbines cannot work if there is no wind, or if the wind speed is so high it would damage them.

Question 23

Explain water power.

Answer 23

Moving water has kinetic energy. This can be transferred into useful energy in different ways. For example:
Wave machines use the up and down movement of waves to turn electricity generators.
Tidal barrages are built across the mouths of rivers. As water moves in or out of the river mouth when the tide turns, the kinetic energy in the water is used to turn electricity generators.
Hydroelectric power (HEP) schemes store water high up in dams. The water has gravitational potential energy which is released when it falls. As the water rushes down through pipes, this stored energy is transferred to kinetic energy, which turns electricity generators.

Question 24

Explain geothermal.

Answer 24

In some places the rocks underground are hot. Deep wells can be drilled and cold water pumped down. The water runs through fractures in the rocks and is heated up. It returns to the surface as hot water and steam, where its energy can be used to drive turbines and electricity generators.

Question 25

Explain solar cells.

Answer 25

Solar cells are devices that convert light energy directly into electrical energy. You may have seen small solar cells on calculators. Larger arrays of solar cells are used to power road signs, and even larger arrays are used to power satellites in orbit around Earth.

Question 26

Explain solar panels.

Answer 26

Solar panels are different to solar cells. Solar panels do not generate electricity. Instead they heat up water directly. A pump pushes cold water from a storage tank through pipes in the solar panel. The water is heated by heat energy from the Sun and returns to the tank. They are often located on the roofs of buildings where they can receive the most sunlight.

Question 27

How can energy be saved?

Answer 27

In power stations using fossil fuels or biomass fuel.
Using wind turbines.
Using hydroelectric power schemes.
Using wave power or tidal power.
Using solar cells.

Question 28

How can we reduce the use of fossil fuels?

Answer 28

Walk to instead of getting using cars where possible.
Turn down the heating.
Turn off the lights when leaving the room.