Unit 1 Energy Flashcards
What are the different types of energy?
-Heat/ thermal-
-Nuclear
-Electrical
-Chemical
-Light
-Sound
-Magnetic
-Kinetic
-Gravitational potential
-Elastic potential
What is the unit of energy?
Joules (J)
-1J is the amount of energy required to lift an averaged sized apple vertically by 1m.
What is the principle of the ‘conservation of energy’?
Energy cannot be created or destroyed. It will change from one form to another. The total amount of energy does not change.
What is the energy transfer equation for ‘striking a match’?
CHEMICAL energy —> HEAT energy + LIGHT energy
What is the definition of ‘non-renewable’ energy resources?
Non- renewable energy resources have a finite supply and will eventually run out. (This is because they are used faster than they can be replaced by nature).
What are examples of non-renewable resources?
Fossil fuels: coal, oil, natural gas, lignite, peat
Nuclear fuels: uranium and plutonium (used in nuclear fission).
What is meant by the terms ‘Nuclear fission’ and ‘ Nuclear fusion’?
Nuclear fission: A HEAVY NUCLEUS IS SPLIT into two smaller, roughly equal nuclei and energy is released.
Nuclear fusion: TWO LIGHT NUCLEI, such as hydrogen, ARE JOINED to form a larger nucleus and energy is released.
How is electricity generated using non- renewable energy resources?
-Fossil fuels are burned to generate heat energy OR nuclear fuels undergo fission, in a reactor, to generate heat energy.
-The heat is used to boil water and create steam.
-The steam is used to drive turbines creating kinetic energy.
-This kinetic energy turns a rotor in a generator to produce electrical energy.
What are the advantages and disadvantages of fossil fuels?
ADVANTAGES:
-Fossil fuel power stations are relatively cheap to start up.
-They are only moderately expensive to run.
-They are relatively large reserves of coal, although other fossil fuels are not as plentiful.
DISADVANTAGES:
-Fossil fuels are non-renewable and will run out.
-They release CO2 when burned, thus contributing to global warming.
-When coal and oil are burned they release sulphur dioxide which causes acid rain.
Describe the ‘greenhouse effect’ and ‘global warming’.
GREENHOUSE EFFECT:
-The earth absorbs radiation from the sun causing it to heat up and emits this heat energy into the atmosphere (as infrared radiation of a longer wavelength) when temperatures drop e.g. at night.
-The greenhouse gas, CO2 (and others such as methane and water vapour) which are found in the atmosphere, absorb a proportion of the emitted heat to prevent temperatures on earth from dropping too low (natural process which prevents huge fluctuations in the temperature on earth).
GLOBAL WARMING:
-A problem arises as more and more fossil fuels are burned, releasing additional CO2 into the atmosphere.
-This traps more heat energy, causing the earth’s temperature to increase.
-This can lead to ice caps melting causing widespread flooding and an increase in storms, droughts and famines.
How is acid rain formed?
Most fossil fuels contain small amounts of the element sulfur and when this burns it combines with oxygen to form sulfur dioxide. This forms an acid in water and when it combines with water vapour in the atmosphere it produces acid rain.
What are the advantages and disadvantages of nuclear fuels?
ADVANTAGES:
-Do not produce CO2.
-Do not emit sulfur dioxide which produces acid rain.
DISADVANTAGES:
-They produce radioactive waste which will remain radioactive for tens of thousands of years.
-A non controversial method of storing radioactive waste cheaply, safely and securely for long periods of time required have yet to be found.
-Nuclear fuels are used for fission are non-renewable and will eventually run out.
-Accidents at nuclear powerplants, although rare, can release dangerous radioactive material which contaminates wide areas, leaving them unstable for decades e.g. Chernobyl in 1986 and Fukushima in 2011.
ADDITIONAL RELEVANT INFORMATION:
-Expensive safety precautions in the construction of nuclear power stations make them dearer to build than fossil fuel stations.
-When a nuclear power station comes to the end of its useful lifespan it must be decommissioned. This means that it has to be dismantled and left in a condition which is safe for humans and the environment.
-Decommissioning of a nuclear power station is a long and expensive procedure. This is because it requires specialist personnel and equipment. It is possible for the decommissioning cost to be higher than the building cost.
What is the definition of ‘renewable’ energy resources?
Renewable energy resources will not run out. (This is because they are replaced by nature in less than a human lifetime).
Describe the different ‘renewable’ energy resources.
1) HYDROELECTRIC POWER-
Water is held at a height in a dam. It is released to flow downhill and drive a turbine to generate electricity. At night when little electricity is needed, the water can be pumped up to the dam again, using cheap electricity.
Advantages:
- Low running costs
- No polluting gases
- Very reliable
- Responds quickly to changes in electricity demand
Disadvantages:
- Only certain sites suitable (wet and hilly)
- Can spoil natural habitat for wildlife and plants
2) TIDAL POWER-
A dam is built across an estuary. A lake behind the dam fills up at high tide and empties at low tide.
The fast flowing water turns turbines.
Advantages:
-Will never run out
- No polluting gases
- Low running costs
- Tides are predictable
Disadvantages:
- Need to build barrage across an estuary with sufficient difference in high and low tide - few suitable.
- Prevents free access to estuary by boats
- Can spoil the natural habitat for marine life
- Electrical supply is not continuous
3) WAVE POWER-
Devices bob up and down on the waves.
This movement can drive a turbine.
Advantages:
-Will never run out
-No polluting gases
Disadvantages:
- Great many generators needed to provide reasonable amounts of energy.
Hazard to boats.
-Electricity supply is unreliable
4) WIND POWER-
Giant windmills are used to turn a turbine to drive electrical generators. Groups of such windmills are called a wind farm.
Advantages:
-Will never run out
-No polluting gases
Disadvantages:
-Unsightly in many areas and produce noise.
-Produce relatively small amounts of electricity, so great many needed taking up land which could be used as farmland.
-Unreliable
-Cannot respond to changes in demand
wind turbine
5) SOLAR POWER-
Photocells use semiconductors which convert light energy from the sun into electricity e.g. in calculators and in space satellites.
When solar cells are joined together they are called an array.
Advantages:
-Will never run out
-No polluting gases
-Useful for small supplies e.g. calculator
Disadvantages:
-Only works when Sun shines (in Britain this is mostly in Summer when we need less energy).
-Produce relatively small amounts of electricity.
6) GEOTHERMAL ENERGY-
Water is heated by the hot rocks beneath the Earth’s surface. This hot water can be pumped and used to heat a building e.g. in Iceland.
Advantages:
-Will never run out
-No polluting gases
Disadvantages:
-Only available in certain parts of the world where hot rocks are close to the Earth’s surface e.g. Iceland.
-Very expensive to drill down a few km to the hot rocks
7) BIOMASS-
Biofuels come from plants, crops or agricultural. They can be burned to produce heat or they can be broken down by bacteria to produce methane gas which can be burnt to drive turbines. Fast growing plants can be used to make alcohol which can be used as a fuel.
Advantages:
-Uses up certain types of waste e.g. animal droppings or vegetable waste can be used to produce methane gas.
-Uses plants which can be easily grown
e.g. some plants produce oil or alcohol for burning.
Disadvantages:
-Plants take up land needed to grow food
-It may not be possible to grow plants quickly enough or in large enough quantities to meet the demand for energy
What is the equation for work done?
Work done= force x distance moved in the direction of the force
wd (J)= Fxd
F (N)= wd/d
d (m)=wd/F
