SP3- Conservation Of Energy Flashcards
What’s chemical energy
Energy is stored in food, fuel and batteries
Tell me about kinetic energy
Energy stored in moving objects
What’s thermal energy
Energy stored in hot objects
What’s strain energy or elastic potential energy
Energy stored in stretched, squashed or twisted materials
What’s gravitational energy
Energy stored in objects in high positions
What’s atomic or nuclear energy
Energy stored inside atoms
What’s light energy
Energy stored in light
What’s sound energy
Energy stored in sound
What’s a system in Physics
Describes something in which we are studying changes
Eg an electrical kettle and its surroundings form a simple system
What’s the law of conservation of energy
Energy can’t be created or destroyed, it can only be transferred from one store to another
This means the total energy transferred by a system is the same as the energy put into the system
What units do we use for measuring energy
Joules (J)
How do we represent energy stores and transfers using diagrams
Use a flow diagram showing the energy transfers
What does a sankey diagram show
Shows the amount of energy transferred - the width of the arrows represents the amount of energy in joules
What is dissipation
When something spreads out
Eg energy I can’t be used for other useful energy transfers when dissipated - it’s wasted
How can friction be reduced between moving parts
Lubrication - oil or other liquids and sometimes
Even gases can be used
What is efficiency
It’s way of describing how good a machine is at transferring energy into useful forms
The efficiency of a machine is given as a number between 0 and 1
The higher the
Number the more efficient the machine
How can we calculate efficiency
Useful energy transferred by the device divided by the total energy supplied to the device
What can reducing the amount of wasted energy mesn
It can increase the efficiency of a device or process
Eg for mechanical processes it can mean reducing friction
Also mean finding ways to make sure all the fuel in an engine is being burned or finding a way of Using the energy transferred by heating that would otherwise be wasted
What is insulation
Slows down the rate at which energy is transferred out of a house by heating
What’s a good example of a thermal conduction
In conduction, vibrations are passed on between particles in a solid
Metals are good thermal conductors and materials such as wood are poor thermal conductors
How can energy be transferred by heating
Conduction - where vibrations are passed on between particles in a solid
In convection - part of a fluid that is warmer than the rest rises and sets up a convection current
What’s the only way in which energy can be transferred in a vacuum
Radiation, infrared radiation can also pass through gases and some solid materials
It’s abstained and emitted easily by dull and dark surfaces
What’s thermal conductivity
How easily energy is transferred by heating
A low thermal conductivity means that energy is not transferred through those materials very easily by heating
Why are materials that contain air good insulators
Becuase air has a very low thermal conductivity so when it’s trapped it can’t form convection currents and so does not transfer much energy
What does the rate at which energy is transferred through a material by heating depend on
The thickness of the material, the thermal conductivity, also on the temperature differences across it
When is the rate of energy transfer reduced
By increasing thickness, decreasing thermal conductivity and decreasing temperature difference
What’s gravitational potential energy
Energy stored Becuase of an objects position in a gravitational field
Any object that is above the surface of the earth contains a store of GPE - every time something is moved upwards it stored more GPE
How can change in GPE be calculated in (J)
Mass (kg) X gravitational field strength (N/kg) X change in vertical height (m)
Tell me the kinetic energy calculation formula
KE on top (J) and 1/2 X mass (kg) X speed^2 (m/s^2)
What are non renewable energy sources
Fuels that will run out one day such as fossil fuels eg coals, oil and natural gas
Why are fossil fuels used
They store a lot of energy and they are easy to store and to use in engines
How do fossil fuels contribute to climate change
They release carbon dioxide, other emissions from power stations contribute to this
How can we reduce pollution
Burning natural gas causes less pollution than burning coal - emit less carbon dioxide and produce the same amount of electricity
How do nuclear power stations damage the environment
They don’t enjoy carbon dioxide or other gases
The waste they produce Is radioactive and some of it will stay radioactive for millions of years and is very expensive to dispose safely and to dismantle safely
There many accidents in nuclear power stations and the stations are designed to contain any radioactive leaks
However if a major accident occurs it can have very serious consequences
Compare a nuclear power station and a fossil fuelled one
A nuclear power station costs a lot more to build and to decommission (dismantle) a nuclear power station than a fossil fuelled one
What are renewable energy sources
energy sources that will not run out eg solar wind or wind energy
Most renewable resources do not emit polluting gases Becuase no fuel is burned
Tell me about solar cells
Convert solar energy directly into electrical energy in solar farms on on house roof tops. Solar energy can also be used in power station or to heat water for use in holes but it’s not available all the time
Tell me about hydroelectricity
Generated by falling water in places where water can be trapped in high reservoirs. It’s available at any time
A hydroelectric power station can be started and stopped very quickly unlike fossil fuel power stations
Tell me about wind turbines
Can be used to generate electricity as long as the wind speed is not too slow or fast - a lot are needed to produce the same amount of energy as a fossil fuelled power station and some people think they spoil the landscape
Tell me about tidal power
Can generate electricity when turbines in a huge barrage (dam) across a river estuary turn as the tides flow in and out
Not available all the time but at predictable times - not many places suitable for barrages in U.K. And they may affect birds or other wildlife that live or feed on tidal mudflats
Underwater turbines can be placed in water currents in the sea To generate electricity
Tell me about biofuels
Can be made from animal wasted or from plants - can be made from waste wood or the parts of plants that are not
Used for food
Some crops are grown specifically
Bio fuels called carbon neutral Becuase when they burn they release the same amount of carbon dioxide that they took from the atmosphere when The plants grew
Energy also need to harvest crops and turn them into fuel so not really carbon neutral
How else can electricity be generated
By waves or from hot rocks underground
Why can’t we only use renewable resources to generate electricity
Most are not available
All the time - it takes a lot of land to obtain energy
From biofuels or other renewable sources such as solar farms
