Topic 3 - Conservation Of Energy Flashcards
Give an example of Chemical energy, kinetic energy, thermal objects, elastic potential energy, gravitational potential energy and nuclear/atomic energy.
Chemical energy - Energy stored in food, batteries and fuel
Kinetic energy - energy stored in moving objects
Thermal energy - energy stored in hot objects
Elastic potential energy - stretched, squashed or twisted materials
Gravitational potential energy - Objects in high positions
Atomic/nuclear energy - Energy stored inside an atom
What is the law of conservation of energy?
Energy cannot be created or destroyed
It can only be transferred from one store to another
What are the units for measuring energy?
Joules (J)
How do you represent energy stores and transfers?
Diagrams like this:
Energy stored in Energy transferred by Energy stored in
moving car ——————————————> Hot brakes
(Kinetic energy) Forces during braking (Thermal energy)
How do you show the amount of energy transferred?
Sankey diagrams
What happens to energy when it is wasted during a transfer?
The energy is dissipated (spread out) and cannot be used for other useful energy transfers
How can friction be reduced?
Lubricant
What is efficiency ?
A way of describing how good a machine is at transferring energy into useful forms.
Number between 0 and 1
Higher the number, more efficient the machine.
How can efficiency of a device be calculated?
Useful energy transferred by the device
Efficiency = —————————————————
Total energy supplied to device
How can you increase efficiency i.e. in mechanical processes?
Reduce amount of wasted energy
E.g. Reduce friction in mechanical processes
Also make sure all fuel is burned or find a way of using the excess heat
What is insulation?
Insulation slows down the rate at which energy is transferred out of a house by heating.
He can energy be transferred by heating in conductors?
- In conduction, vibrations are passed in between particles in a solid.
- Metals are good thermal conductors and materials such as wood or poor thermal conductors. (Good thermal insulators)
How can Energy be transferred by heating in a convection?
In convection, part of a fluid that is warmer than the rest, rises and sets up a convection current.
How can Energy be transferred by heating by Radiation?
Radiation is the only way in which energy can be transferred through a vacuum.
Infrared radiation can also pass through gases and some solid materials.
Infrared radiation is absorbed and emitted easily by dull, dark surfaces, and is absorbed and emitted poorly by light, shiny surfaces.
What is thermal conductivity?
Energy is not transferred through very easily by heating
How does thickness, conductivity and temperature affect energy transfer?
Rate of energy transfer is reduced by:
- Increasing thickness
- Decreasing thermal conductivity
- Decreasing temperature difference
What is Gravitational potential energy?
Energy that is stored because of an object’s position in a gravitational field.
- Any object that is above the surface of the Earth contains a store of gravitational potential energy
- Every time something is moved upwards, it stores more gravitational potential energy
What is the equation for the change in gravitational potential energy?
Change in gravitational
potential energy = mass x gravitational x change in vertical
(J) (Kg) field strength height
(N/kg) (m)
What is most electricity in the Uk generated from?
Nuclear fuels or fossil fuels {coal, oil and natural gas}
What does non-renewable mean?
Energy sources that will run out {we can’t produce them at a rate we can replace them}
What are fossil fuels used for?
Petrol and diesel > Vehicles, aeroplanes and ships because they store a lot of energy and are easy to store in engines.
Natural gas > Burnt to heat homes or cooking
How do fossil fuels affect climate change ?
Burning fossils fuels emit carbon dioxide and other gases.
Carbon dioxide emissions contribute to climate change by warming the atmosphere.
What other problems do Fossil Fuels cause?
Cause pollution problems and reducing pollution costs a lot of money.
Burning natural gas causes less pollution than burning coal.
Therefore, power stations with natural gas cause less pollution than those with coal, when producing the same amount of electricity
How are nuclear power stations beneficial and bad?
Don’t emit any carbon dioxide.
Not many accidents as designed to contain radioactive leaks
However, when one does happen it causes bad consequences.
Waste they produce is very radioactive and will stay that way for millions of years.
This is expensive to dispose of safely.
Very expensive to decommission (dismantle safety) a nuclear power station when it is done with.
Costs a lot more to build and decommission a nuclear power station than a fossil fuelled one.
