Energy

Question 1

What is energy?

Answer 1

• We need energy to walk, to lift objects, to push, to pull and to think
• We get our energy from food and it is transferred into other forms of energy such as kinetic energy and heat energy
• Energy is the ability to work e.g. to make something happens or to have the potential to do so

Question 2

Energy types

Answer 2

Chemical, heat, sound, light, electrical, gravitational potential, kinetic, elastic potential, nuclear

Question 3

Chemical energy

Answer 3

Energy that is stored (potential) in food or batteries which can be transferred into other forms of energy. It is the energy stored in chemical bonds

Question 4

Internal/ Heat energy

Answer 4

The wasted energy in many energy transfers is usually this. Most energy is wasted by turning into this. Thermal energy refers to the transfer of heat energy (from a Bunsen burner flame to increase the internal energy of. beaker of water

Question 5

Sound energy

Answer 5

A series of longitudinal waves detected by our ears. Can also be another example of wasted energy e.g the hum from a fridge

Question 6

Light energy

Answer 6

A series of electromagnetic detected by the eye. e.g. the light bulb emits this energy

Question 7

Electrical energy

Answer 7

Arguable our most useful form of energy. Devices we use transfer this form of energy to other useful forms e.g the light bulb

Question 8

Gravitational potential

Answer 8

A form of stored energy that varies depending on where you are in a gravitational field. The higher up you are, the more GPE you have

Question 9

Kinetic energy

Answer 9

The energy stored in an object. Electrical motors transfer electrical energy to kinetic energy in devices such as hairdryers, food, mixers, etc

Question 10

Elastic potential energy

Answer 10

Energy stored in an object such as a spring that is stretched, squashed or bent. It’s sometimes referred to as strain energy or simple, elastic energy

Question 11

Nuclear energy

Answer 11

Nuclear energy is energy in the nucleus of an atom. This energy can be released when unstable uranium atoms in a nuclear reactor split apart in a process known as nuclear fission

Question 12

Energy transfer and efficiency

Answer 12

• When we run, chemical energy from our food is converted into kinetic energy. Some of it is wasted by being transferred into thermal energy, making us hot and increasing our internal (heat) energy
• When a portable fan is used, chemical energy from a battery is converted into electrical energy, transferred along wires to a motor which then converts it into kinetic energy. Some energy is wasted as sound. Energy is also wasted because the internal energy of wires increases as they get warm
• Energy will never disappear. It can only be wasted or converted into other forms of energy. This is known as the law of conservation of energy “energy connoted be created or destroyed in any process. It can only be transferred from on type of energy to another”

Question 13

Energy transfer

Answer 13

When we are considering energy transfers, we must remember that a proportion of the energy input is wasted. We can never have 100% efficiency. The useful output energy will always be less that the input

Question 14

Formula for efficiency

Answer 14

Efficiency= useful energy output/ total energy input

Question 15

Power

Answer 15

• Power rating of a motor driven pulley system tells us how quickly it transfer electrical energy into GPE
• Power is the rate of transfer of energy or work
• Power (P) is measured in watts (W). 1 W is equal to a transfer of 1J of energy per seco

Question 16

Formula for power

Answer 16

Power= work done/ time taken

Question 17

Energy resources

Answer 17

• A renewable source of energy can be used over and over again. There is an unlimited supply e.g. wood as trees can be grown, water is unlimited, wind
• Non-renewable energy sources will eventually run out and cannot be replaced e.g. coal because it takes a long time to form and we are using it a very fast rate

Question 18

Wind

Answer 18

• Wind is caused by huge convection currents in the Earth’s atmosphere, driven by heat energy from the sun. This moving air has huge amounts of kinetic energy which can be transferred into electrical energy using turbines
• KE -> Electrical energy
• Wind is renewable, no CO2, but it is very noisy and wind turbines are ugly

Question 19

Waves

Answer 19

• Waves are caused by the action of the wind upon the sea. Wave machines use the up and down movement of waves and air in a chamber to work electricity generators
• KE -> Electrical energy
• Renewable, no greenhouse gases but hard to build and expensive

Question 20

Tides

Answer 20

• Tidal barrages are built across the mouths of rivers entering the sea. As water moves in and out of the river mouth when the tide turns, kinetic energy is used tow rod electricity generators
• Ke -> electrical
• Renewable, no Co2, but expensive, harms wildlife and requires the right geography

Question 21

Hydroelectric

Answer 21

• These power schemes store water high up behind dams. The water has gravitational potential energy. As water rushed down through pipes, this GPE is transferred to kinetic energy, which turns electricity generators
• Ke -> electrical
• Renewable, no CO2 but ugly, disrupts wildlife, expensive

Question 22

Geothermal

Answer 22

• In some places, rocks underground are hot because of radioactive decay. Deep wells can be drilled and cold water pumped down to be heated by rocks. It returns to the surface as hot water and steam, where its energy can be used to drive turbines and electricity generators
• thermal energy -> KE -> electrical
• Renewable, but deep drilling is difficult and expensive

Question 23

Solar heating

Answer 23

• Solar panels do not generate electricity. Instead the sun is used to heat up water directly. A pump pushes cold water from a storage tank through pipes in the solar panel to be heated
• thermal energy -> electrical
• Renewable but sun’s energy varies

Question 24

Solar cells

Answer 24

• Devices that convert light energy directly into electrical. Large arrays of solar cells are used to power road sings, and even larger arrays are used to power satellites in orbit around the Earth
• Light energy -> electrical
• Renewable, but sunshines varies, expensive and not super efficient

Question 25

Fossil fuels

Answer 25

Coal, oil, natural gas are called fossil fuels. Chemical energy from the remains of plants and Dead Sea creatures that lived millions of years ago is stored within these. This energy is transferred to thermal energy and light energy when the fuels burn

• Chemical energy -> heat energy -> Kinetic energy -> electrical
• Efficient, reliable but non renewable and causes pollution

Question 26

Nuclear power

Answer 26

• Heat from the chain reaction called by the fission of unstable uranium nuclei is used to boil water which produces steam, that turns turbines
• Nuclear -> thermal -> Kinetic -> electrical
• No greenhouse gases, cheap to run but expensive to build, nuclear waste

Question 27

Biomass

Answer 27

• Fuels come from living things like wood. Chemical energy stored in these when burned is released as heat energy which heats up water into steam. Steam is then used to turn turbines which generate electrical
• Chemical -> Heat -> Kinetic -> electrical
• Renewable, carbon neutral but huge land area needed