Topic 3 - Conservation of energy Flashcards
What does conservation of energy mean?
Energy is never created or destroyed
the total energy of a closed system has no ….
net change
Energy can be… (3)
stored, transferred between stores and dissipated
What are the 4 main ways in which energy can be transferred?
1- Mechanically
2- Electrically
3- By heating
4. By radiation
Describe the energy changes in a ball rolling up a slope
The ball does work against the gravitational force, so energy is transferred mechanically from the kinetic energy store of the ball to its gravitational potential energy store
Describe the energy changes in a bat hitting a ball
The bat has energy in its kinetic energy store. Some of this is transferred mechanically to the ball’s kinetic energy store. Some energy is also dissipated as sound and heat
Describe the energy changes in a rock dropped from a cliff
The rock accelerates to the ground due to gravity so energy is transferred from the rocks GPE store to its KE store
Describe the energy changes in a car slowing down
Kinetic energy is transferred mechanically (friction) and then by heating, to the thermal energy stores of the car and road
Describe the energy changes in a kettle, that is boiling water
Energy is transferred electrically from the mains to heating element of the kettle, and then by (heating), to the thermal energy store of the water
When do mechanical processes in objects become wasteful?
When they cause a rise in temperature (when heat energy is dissipated to its surroundings)
What is the effficiency equation?
Efficiency = (useful/total) * 100
What can reduce energy transferred by FRICTION?
Lubrication
What can reduce the rate of energy transfer by HEATING?
Insulation (so if a house was insulated, the house would be warmer for longer as heat wont be transferred outside the walls of the house)
What are 2 methods of home insulation?
- Cavity walls
- Having walls with low thermal conductivity
- Thicker walls
Give examples of non-renewable resources
- Fossil fuels
- Nuclear energy
What are advantages of non-renewable energy resources?
- They’re reliable
2. Theyre cheap
What are disadvantages of non-renewable energy resources?
- They’re running out
- They can cause environmental problems e.g. global warming/acid rain
- Oil spillages can destroy habitats
- Nuclear waste is very dangerous and difficult to dispose of
Give examples of renewable energy resources
- bio-fuels
- Wind
- Tidal
- Solar
- Hydro-electric
Evaluate the use of bio-fuels (burning plants and animal waste)?
- They’re supposedly ‘carbon neutral’
- They’re fairy reliable
- They’re renewable
BUT - They’re expensive
- Lots of species lose their habitats
Evaluate the use of wind power (wind rotating blades in a turbine, connected to a generator to produce electricity)
- No pollution
- Initial costs are quite high but running costs are minimal
BUT - They can spoil the view
- Not reliable as it needs to be windy
- Noise pollution
Evaluate the use of solar power (materials in solar cells use energy transferred by light to create an electric current)
- No pollution
- Initial costs are high, but there are no running costs
BUT - Not reliable
Evaluate the use of hydro-electricity (generating electricity by moving water)
- No pollution
- Very reliable
- Supplies a large amount of electricity
BUT - expensive
- loss of habitats for animals
Evaluate the use of tidal barrages (generating electricity in estuaries by water turning a turbine)
- No pollution
- quite reliable (they always happen twice a day)
- Initial costs are quite high but there are no fuel costs and running costs are minimal
BUT - They can affect boat access (estuaries), can spoil the view and alter habitats for wildlife
- The height of the tides may not always be the same
What energy resources do the uk use currently?
- Fossil fuels and nuclear power
- wind power
Energy resources are beginning to become chosen for their effect on the …
environment
people have started using electric cars and hybrids
What is the use of renewables usually limited by?
Reliability and money
Research into improving the reliability and cost of renewable resources takes…
time and money
