Energy Stores and Transfers

Question 1

What is the formula for gravitational potential energy?

Answer 1

Gravitational potential energy = mass x gravity x height
Egp = mgh
J = kgN/kgm

Question 2

What is the formula for kinetic energy?

Answer 2

Kinetic energy = 1/2 x mass x velocity^2
Ek = 1/2mv^2
J = 1/2kgm/s

Question 3

What is efficiency?

Answer 3

The amount of useful output of something compared to the wasted output

Question 4

What is the formula for efficiency?

Answer 4

Efficiency = (Useful energy out (J) / Total energy in (J)) x 100

Question 5

What is a sankey diagram?

Answer 5

A diagram showing the efficiency of a device by showing input energy and its useful and wasted output energy

Question 6

What are the three types of heat energy transfer?

Answer 6

Conduction - particles bumping together and transferring energy to each other
Convection - fluid particles being heated, rising, cooling, sinking, and being heated again
Radiation - infrared radiation being emitted out by all objects with heat

Question 7

What are advantages and disadvantages of renewable energy resources?

Answer 7

They will never run out. They damage the environment, but less badly than non-renewables. They do not provide much energy and some are unreliable.

Question 8

What has been the trend in the UK’s energy use?

Answer 8

Over the 20th century electricity use rapidly increased. Since the start of the 21st century it has been slowly declining from more efficient appliances. Most of our electricity comes from fossil fuels and nuclear power. We are trying to increase use of renewable energy sources.

Question 9

What are the types of energy?

Answer 9

Magnetic
Kinetic
Heat (Thermal)
Light
Gravitational potential
Chemical 
Sound
Elastic potential 
Electrostatic
Nuclear
Most Kids Hate Learning GCSE Energy Names

Question 10

What is conservation of energy?

Answer 10

Energy can be stores, transferred between stores, and dissipated, but it can never be created or destroyed. In a closed system energy has no net change.

Question 10

How can energy be transferred between stores?

Answer 10

Mechanically - forces doing work
Electrically - charge doing work against resistance
By heating
By radiation

Question 11

How does lubrication help increase efficiency?

Answer 11

When something, friction acts against it, wasting energy as heat. Lubricants coat objects touching each other, reducing friction so increasing efficiency.

Question 12

How does insulation help?

Answer 12

Materials with lower thermal conductivities transfer heat poorly by conduction. Walls are made of low thermal conductivity materials to slow energy transfer through them. Some houses have cavity walls, with an air gap, as air conducts heat very poorly. Thicker walls also slow energy transfer rate.

Question 13

What are the advantages and disadvantages of using fossil fuels?

Answer 13

They are reliable. Plants can respond quickly to changes in demand. Plants are cheap to build and run.
They are running out. They release CO2, contributing to global warming. Coal and oil can release SO2, causing acid rain. Oil spillages damage the environment.

Question 14

What are the advantages and disadvantages of using nuclear energy?

Answer 14

It is reliable and can respond to demand. It does not produce CO2 and other pollutants.
Plants are expensive to build and safely decommission. Nuclear waste is dangerous and difficult to dispose of. There is a risk of meltdowns.

Question 15

How do bio-fuels work?

Answer 15

They are created from plant products or animal waste. They can be burned to produce electricity or run cars. They are supposedly carbon neutral and can be grown fairly quickly. It is expensive to refine them and food crops may be burned instead. Some forests have been cleared to grow them.

Question 16

How does wind power work? What are the advantages and disadvantages?

Answer 16

There are generators in each turbine. Wind turns the blades, rotating the generator and producing electricity.
There is no pollution and low running costs.
The initial cost is quite high, they do not produce much power individually, they can spoil the view and be noisy, and they only work when it is windy.

Question 17

How does solar power work? What are the advantages and disadvantages?

Answer 17

Solar cells are made from materials that use energy from light to create a current.
It can be used in remote places such as deserts, there is no pollution, there are almost no running costs, they can be put on homes.
They use quite a lot of energy to make, they do not work as well in cloudy countries, and they do not work at night.

Question 18

How does hydro-electricity work? What are the advantages and disadvantages?

Answer 18

A valley is flooded and a dam is built. Rainwater is caught and allowed out through turbines.
There is no pollution, production can be increased in times of high demand, and there are minimal running costs.
The environment is impacted in the valley and initial costs are high.

Question 19

How do tidal barrages work? What are the advantages and disadvantages?

Answer 19

They are big dams build across river estuaries with turbines. As the tide comes in the estuary fills up, and water is let out through turbines at a controlled speed.
There is no pollution, it is quite reliable, and running costs are minimal.
Boat access is affected, they can spoil the view, they alter wildlife habitats, and initial costs are quite high.

Question 20

What limits the use of renewable energy sources?

Answer 20

Building new plants is expensive. People often do not want new plants near them. Some resources are not as reliable as fossil fuels.