SP3 Conservation of Energy Flashcards
What are the different ways energy is stored in?
- chemical
- kinetic
- thermal
- elastic potential
- gravitational potential
- nuclear
- magnetic
- electrostatic
Define chemical energy
Energy between bonds
Define kinetic energy
Energy stored in moving objects
Define thermal energy
Energy stored in hot objects
Define elastic potential energy
Stored in stretched, squashed or twisted materials
Define gravitational potential energy
Energy stored in high positions of objects within a gravitational field
Define nuclear energy
Energy stored within atoms
Define magnetic energy
Energy stored within a magnetic field
Define electrostatic energy
Energy between two charges
State the law of conservation of energy
Energy cannot be created or destroyed, only stored and transferred. This means that all energy in a system has to go somewhere, it can’t be lost
What are the units for energy?
J (Joules)
Give an example of magnetic energy
- magnets
- compasses
Give an example of thermal energy
- human bodies
- hot coffees
- stoves
Give an example of chemical energy
- food
- muscle cells
- electrical cells
Give an example of kinetic energy
- runners
- buses
- comets
Give an example of nuclear energy
- uranium nuclear power
- nuclear reactor
Give an example of electrostatic energy
Thunderclouds
Give an example of elastic potential energy
- springs
- inflated balloons
Give an example of gravitational potential energy
- planes
- kites
- mugs on a table
What are Sankey diagrams?
- Used to show the amount of energy transferred
- width of the arrow represents the amount of energy in joules
How can energy be transferred?
- mechanical work
- electrical work
- heating
- radiation
Define mechanical work
A force moving an object through distance
Define electrical work
Charges moving due to a potential difference
Define heating as a method of energy transfer
Due to temperature difference caused electrically or by chemical reaction
Define radiation as a method of energy transfer
Energy transferred as a wave
What are the two different types of radiation?
- conduction
- convection
Why does conduction occur?
Vibration of particles due to heating. This vibration moves along the material, thereby moving the heat energy
In what materials does conduction take place?
Solids: mainly in metals
When does convection occur?
When part of a fluid is warmer than the rest and rises
Describe a convection current
Warm air rises and cold air sinks, so warm air is at the top and cold air is at the bottom
In what materials does convection occur?
Liquids and Gases
What is a conductor?
A material in which heat and electricity can pass through easily
What is an insulator?
A material in which heat and electricity cannot pass through easily
Define thermal conductivity
A measure of how quickly energy can be transferred via conduction through a metal
What is the rate of energy transfer reduced by?
- increasing thickness
- decreasing thermal conductivity
- decreasing temperature difference
What is efficiency?
A way of describing how good a machine is at transferring useful energy, in comparison to its input
What is the formula for efficiency?
useful energy/total energy
How can mechanical devices be made more efficient?
Lubricant to reduce friction between its moving parts
What is the formula for gravitational potential energy?
m x g x change in h
What is the formula for kinetic energy?
1/2 x m x v^2
Define non-renewable resource
Resources that are not replenished; they will run out someday
Give some examples of non-renewable resources
- coal
- oil
- natural gas
- nuclear fuels
What are the advantages of coal?
- can be used for old-fashioned trains
- burnt in fireplaces and barbecues
What are the advantages of oil?
- petrol and diesel are fossil fuels made from oil
- store a lot of energy
- easy to store and use in energies
What are the advantages of natural gas?
- causes less pollution than burning coal
- emits less CO2 than other fossil fuel powered stations while producing the same amount of energy
What are the advantages of nuclear fuel?
- stores a lot of energy in small amounts
- useful for spacecraft where the mass of the fuel is important
- reliable as it meets current demand
- relatively cheap
- clean: doesn’t release any greenhouse gases/ harmful chemicals into the atmosphere
What are the disadvantages of coal?
- carbon dioxide is produced
- expensive
- contributes to climate change
What are the disadvantages of oil?
- harmful energy produced that contributes to global warming
- will run out one day
- releases sulfur impurities which causes acid rain
What are the disadvantages of natural gas?
- harmful gases produced
What are the disadvantages of nuclear fuel?
- highly radioactive waste produced which is difficult to get rid off
- overall cost of nuclear fuel is high
Define renewable resource
A resource that will be replenished; it will never run out
Give some examples of renewable resources
- geothermal
- water waves
- solar cells
- hydroelectricity
- wind
- tidal
- biofuels
What are some advantages of solar energy?
- can convert solar energy directly into electrical energy
- can be used anywhere
- no pollution
- free energy
- low running costs
- doesn’t produce co2
What are some advantages of hydroelectricity?
- available at any time as long as reservoirs don’t dry up
- can be started and stopped quickly unlike fossil fuel power stations
- can produce large amounts of energy and provide an immediate response for demand
What are some advantages of wind turbines?
- produces no co2
- efficient as it produces electricity 70-85% of the time
What are some advantages of tidal power?
- no fuel costs and minimal running costs
- reliable: happens twice a day without fault
- significant amount of energy generated
What are some advantages of geothermal power?
- heats buildings directly without the need to generate electricity
- reliable free energy
What are some advantages of biofuels?
- overall process is carbon neutral
- fairly reliable: short time to grow crops + crops can grow all year round
- can be made from waste food
What are some advantages of wave power?
- fairly useful to generate electricity on a small scale
- no fuel costs
- minimal running costs
What are some disadvantages of wave power?
- many required to produce sufficient energy: spoils the view
- unreliable: depends on wave motion
- initial costs high
- structures can disturb habitats and are hazardous to boats
What are some disadvantages of biofuels?
- extra energy is needed to grow the crops or feed the animals
- competition for space and water with crops that are grown for food
What are some disadvantages of geothermal energy?
- difficult to find suitable location
- cost of building is high
What are some disadvantages of tidal power?
- structure spoils view
- not many places suitable for barrages
- disturbs habitats
- prevents free access by boats
- high initial manufacturing costs
What are some disadvantages of wind turbines?
- can be noisy
- large number needed to produce sufficient energy
- ruins scenery
What are some disadvantages of hydroelectricity?
- a possibility of flooding the valley, leading to rotting vegetation
- needs a constant supply of falling water
- loss of habitats
- inconvenient: some villages evacuated to build
What are some disadvantages of solar energy?
- not available all the time
- initial costs high
- solar power only works when the sun is out in the daytime
- can require a lot of space
- only powers some homes
How can efficiency be increased?
- reducing waste output
- recycling waste output
How is heat loss prevented in buildings?
- thicker walls mean greater thermal insulation: less heat loss
- air cavities between walls causes lots of heat loss through convection, which is solved through a cavity wall
How can we reduce wasted energy?
- lubricate systems: less friction and heat created
- thermal insulation: less heat lost
