P1: Energy

Question 1

What is an energy system?

Answer 1

An energy system is a group of objects that have the capacity to do work

Question 2

What are the eight stores of energy?

Answer 2

+ Kinetic [Movement of objects]
+ Thermal [Temperature of objects]
+ Chemical [The Energy of chemical substances & Reactions]
+ Nuclear [Energy stored in atoms]
+ Gravitational Potential energy [The energy stored by an object at an altitude]
+ Elastic potential energy [The energy stored by an elastically deformed object]
+ Magnetic [The energy of attraction between overlapping magnetic fields]
+ Electrostatic [The energy of attraction between two oppositely charged materials]

Question 3

What are the four ways energy can be transferred between stores?

Answer 3

+ Via radiation (Electromagnetic Waves)
+ Via Mechanical forces (Normal contact force, friction, tension)
+ Via electrical currents
+ Via thermal conduction (Heat)

Question 4

What are the three equations for working out how much energy is transferred?

Answer 4

+ Energy (J) = Force (N) x Distance (m)
+ Energy (J) = Spring Constant (N/m) x Extension (m)
+ Energy (J) = Potential Difference (V) x Charge (C)
Note: Energy transferred = Work done

Question 5

What is the equation that allows us to calculate the kinetic energy of an object?

Answer 5

Kinetic energy (J) = 0.5 x Mass (kg) x Velocity (m/s) x Velocity (m/s)

Question 6

What is the equation that allows us to calculate the Elastic potential energy of an object?

Answer 6

Elastic Potential Energy (J) = 0.5 x Spring Constant (N/m) x Extension (m) x Extension (m)

Question 7

What is the equation that allows us to calculate the gravitational potential energy of an object?

Answer 7

Gravitational Potential energy (J) = Mass (kg) x Height (m) x Gravitational Field Strength [9.81] (N/kg)

Question 8

What is the equation that allows us to work out the energy stored or released when heating/cooling an object?

Answer 8

Change in Energy (J) = Mass (kg) x Change in temperature (Degrees Centigrade) x Specific Heat Capacity (J/kg’C)
Note: The specific heat capacity of a substance is the energy required to raise the temperature of one kilogram of that substance by one degree centigrade

Question 9

What is the equation for power & the rate of energy transfer?

Answer 9

Power (W) = Energy transferred (J) / Time (s)

Question 10

What is the law for the conservation of energy?

Answer 10

Energy can neither be created nor destroyed, but can only be stored, transferred or dissipated

Question 11

What is a closed energy system?

Answer 11

In a closed energy system, neither mass nor energy can escape from the system. This means the total level of energy within the system will remain the same regardless of what energy transfers occur

Question 12

What is meant by the term energy efficiency?

Answer 12

+ When transferring energy to fulfill a purpose, not all of the energy transferred goes into the desired stores. A proportion of it is ‘wasted’ as the energy dissipates into the thermal store
+ The energy efficiency of an energy transfer is a percentage showing how much energy is actually transferred as is intended. It can be worked out with the below equations:
> Efficiency (%) = 100 x (Useful Energy Output (J) / Total Energy Input (J))
> Efficiency (%) = 100 x (Useful Power Output (W) / Total Power Input (W))

Question 13

How is energy wasted in houses, and how can this wasted energy be reduced?

Answer 13

+ Materials such as brick, wood, glass & concrete in houses have high thermal conductivity, meaning they transfer a high amount of energy wastefully as thermal energy
+ To reduce these wasteful energy transfers, Insulators can be used in the following ways:
> foam can be placed in the cavities of walls
> Fibreglass can be placed in the lofts of buildings
> An insulating layer of air can be trapped in double-glazed windows

Question 14

How is energy sourced & generated in the world?

Answer 14

+ Energy can be generated using Renewable & Non-Renewable methods
> Renewable methods are infinite, replenish in the short term and are sustainable for the wider world & environment
> Non-renewable methods are finite, do not replenish and are harmful to the wider world & environment

Question 15

How is the generated energy used in society?

Answer 15

+ Energy resources are used to fuel…
> Transport (Cars, trains, aeroplanes etc.)
> Standard Usage in Industry, homes, lighting, commerce
> Heating of buildings
+ Also used in residential, transport, commercial & industrial sectors

Question 16

How does coal produce electricity?

Answer 16

+ Coal is mined from the earth & burnt to produce smoke, or to warm a vat of water to produce steam, both of which rotate a turbine
+ Coal is a fossil fuel, meaning it is non-renewable and produces Carbon dioxide emissions. It is also dangerous to mine for the miners.
+ Previously there were large quantities of coal in the UK that were inexpensive to mine, but all major coal mines in the UK have since shut down

Question 17

How is oil used as an energy source?

Answer 17

+ Similarly to coal, oil is a fossil fuel that can be burnt to produce energy
> However, it large quantities can also be refined to make fuel for vehicles
+ Large reserves of oil are becoming difficult to find & extract
> Oil requirements in ACs means its supplies are influenced by politics
+ Transporting & refining the oil is relatively easy though

Question 18

How is natural gas used as an energy source in the UK?

Answer 18

+ Natural gas, another fossil fuel, is used for heating & electricity generation in homes & industrial settings
+ It is cleaner than burning oil or coal
+ It is relatively easy to transport & store
+ The UK has good gas reserves, however most of them are off-shore, difficult and expensive to extract

Question 19

What is Nuclear energy?

Answer 19

+ Nuclear energy is produced through the nuclear fission of Nuclear supplies, such as uranium. This produces heat and creates steam, which rotates a turbine.
+ Despite requiring extracted resources, nuclear energy is a possibly indefinite supply of energy (However it is still considered Non-renewable)
+ Its an extremely efficient process, generating lots of energy for little fuel
+ Expensive to start up and decommission power plants
+ No real solution has been found to deal with nuclear waste
+ There is a danger of nuclear accidents and the release of radioactive material into the environment
> Therefore, security at power plants is an issue

Question 20

What is Hydroelectric Power?

Answer 20

+ Hydroelectric power is sourced from the movement of water in lakes, reservoirs, dams & rivers
+ Is costly to construct & can flood local communities & landscapes
+ Creates water reserves & on-demand energy

Question 21

What is Solar Energy?

Answer 21

+ Solar energy is an intermittent renewable energy source, which harnesses energy from the sun by containing it within photovoltaic cells
+ Houses can have their own powered electricity & heating
+ The manufacturing & installation of solar panels is expensive

Question 22

What is Tidal Energy?

Answer 22

+ Energy sourced from the ocean tides driving turbines. Tidal barrages trap water at estuaries during high tide, and release it through turbines at low tide.
+ Tidal barrages can help prevent flooding & the power is good for island nations like the UK
+ Only a few estuaries are suitable, and tidal barrages can damage ecosystems
+ Tidal barrages are also very expensive

Question 23

How is electricity generated from the wind?

Answer 23

+ The wind rotates a wind turbine, which in turn rotates a generator & produces electricity
+ It is an unreliable but renewable energy source & can be used as individual units
+ Some consider them an eyesore, and they can be expensive to construct

Question 24

What is geothermal energy?

Answer 24

+ Geothermal energy uses steam from cold water pumped into the ground of volcanic regions to rotate a turbine
+ It can be expensive to set up & can only be used in volcanic regions
+ It is a renewable energy source & has been successful in iceland & New Zealand

Question 25

How is biomass used to produce electricity?

Answer 25

+ Biomass is when organic material is burnt to generate heat & electricity.
> Biomass can also be treated with chemicals for use in vehicle engines
+ Cheap & readily available method
+ If the organic material is replaced, it can be a long term sustainable way of generating renewable energy
+ Growing biomass consumes arable land
+ Burning Biomass produces greenhouse gases

Question 26

How can waves be used to generate electricity?

Answer 26

+ Movement of water against an onshore cavity compresses air and rotates a turbine
+ Only used in small, local projects (as opposed to national ones)
+ Produces minimal electricity & can be expensive

Question 27

How is energy usage in the UK reliable & secure?

Answer 27

+ The UK uses a mixture of energy sources, so a disruption in resource supply doesn’t affect distribution
+ Furthermore, fossil fuels & Nuclear energy can be reliably used at any point to give a continuous supply of energy
> Energy from wind & solar energy is unreliable, as their sources fluctuate

Question 28

How have world energy trend changed?

Answer 28

+ An increasing population leads to an increasing energy demand
+ Renewable energies produce 20% of global energy
> This isn’t predicted to change until 2035
+ Future legislation will dictate fossil fuel trends & dwindling fossil fuel sources will mark a shift towards renewables