Topic 1 - Energy Flashcards
What is a system?
An object or group of objects
What happens when the system changes?
There are changes in the way the energy is stored
Name five ways energy stores are changed when embers systems change.
- object projected upwards
- moving object hitting an obstacle
- object accelerated by a contestant force
- vehicle slowing down
- boiling water in a kettle
What are the 8 energy stores?
- thermal
- kinetic
- gravitational potential
- elastic potential
- chemical
- magnetic
- electrostatic
- nuclear
How is energy transferred?
Mechanically (by a force doing work)
Electrically (work done by moving charges)
Heating
Radiation
What is kinetic energy?
Anything that is moving
How do you calculate kinetic energy?
1/2 x mass kg x speed (squared) m/s (squared)
What is gravitational energy?
Raising an object above ground level rwhuch requires work
How do you calculate gravitational potential energy?
Mass x height x gravitational field strength N/Kg
What is elastic potential energy?
The amount of energy stored in a stretched spring
How do you calculate elastic potential energy?
1/2 x spring constant N/m x extension (squared) m
How do you calculate the amount of energy stored in or released from a system as its temperature changes?
Mass x specific heat capacity J/kg*C x temperature change *C
What is specific heat capacity of a substance?
Amount of energy required to raise the temperature of one kg of the substance by one degree Celsius
Define power.
The rate at which energy is transferred of work is done.
How do you calculate power?
- Energy transferred / time
- work done J / time
What is an energy transfer one 1 joule per second equal to?
A power of 1 watt
What ways can energy be transferred?
Usefully, stored or dissipated
Can energy be created or destroyed?
No
What is dissipated energy?
Wasted energy as when energy is transferred not all of it is useful
Describe energy transfers for a closed system?
Energy can be transferred from the thermal energy store to useless thermal energy store
Energy transfers have occurred within the system but no energy has left the system
How do you reduce unwanted energy transfers?
Thermal insulation
Lubrication
What happens to an energy transfer when the thermal conductivity of a material is high?
The rate of energy transfer by conduction across the material is higher
What is lubrication?
Frictional forces cause some energy to be dissipated
Lubricants reduce frictional forces
How does insulation work?
Reduces the rate or energy transfer by heating
- thick walls with low thermal conductivity slow down the theatre if energy transfer
- thermal insulation such as: double glazed glass, fraught excluders, cavity walls
How do you calculate efficiency?
Useful output energy transfer / total input energy transfer
Useful power output / total power input
How can you increase the efficiency of an intended energy transfer?
Insulated objects
Lubrication
Streamline objects
What are the 9 main energy resources on earth?
Fossil fuels (coal, gas, oil) Nuclear fuel Biofuel Wind Hydro electricity Geothermal Tides Sun Water waves
What is a renewable energy source?
One that can be replenished as its used
Less nasty for environment than no renewables
Don’t provide much energy + unreliable
What uses energy resources?
Transport
Electricity generation
Heating
What are non-renewable energy sources?
They will run out
They damage our environment
Provide most of our energy
Give examples of non-renewable energy stores.
Fossil fuels or nuclear fuels (uranium or plutonium)
How can energy resources be used for transport?
Non renewable: petrol and diesel vehicles use fuel from oil, coal in steam strains
Renewable: vehicles that run on biofuels
How can energy resources be used to heating?
Non renewable: natural gas for hot water, coal in fires, electric heaters
Renewable: geothermal heat pumps, solar water heaters, burning biofuel or using electric heaters
What can some resources be unreliable?
Depend on weather
Evaluate wind power.
Wind turbines have generators inside them which is turned by the rotation of the blades No pollution but spoil views Noisy Dependant on wind speed Initial costs are high No permanent damage to landscape
Evaluate solar power.
Solar cells use sunlight Best for things which require little energy like calculators Used in remote places No pollution Very reliable Can’t increase power output High initial costs
Evaluate geothermal power.
Possible in volcanic areas from the slow decay of radioactive elements
Free reliable energy
Little damage
Can generate electricity or heat buildings
No many suitable locations for power plants
Power plants are expensive
Evaluate hydroelectricity.
Requires flooding of dams to let uhh turbines No pollution Big impact on environment Immediate response to increased demand Reliable unless sin drought High initial costs Small scale
Evaluate wave power.
Small wave powered turbines located around coast which move generators No pollution Disturbs sea bed + spoils view Hazard to boats High initial costs Large scale
Evaluate tidal barrages.
Big dams built across estuaries with turbines inside to control output
Produced by gravitational pull of sun and moon
No pollution
Altering habitat + spoil view + stops boats
Reliable
Initial costs are moderately high
Only some locations
Evaluate biofuels.
Renewable from plant products or animal poo that are burnt
Carbon neutral
Reliable - crops grow quickly
Can’t respond to immediate energy demands
Can be stored
Very expensive
Lots of space
Loss of natural habitats for space
Decay and burning causes CO2 and methane emissions
Evaluate non renewables.
Reliable but slowly running out
Cost effective
Release CO2 - add to greenhouse effect + global warming
Release NAO2 - causes acid rain
Coal mining and oil spillages destroy landscapes
Nuclear waste is dangerous but cheap
How has electricity use changed over time?
20th C - huge increase
21st C - decreasing slowly as we are making more efficient appliances and more careful with energy
How is most of our electricity Produced?
Fossil fuels and nuclear power
What have triggered the move towards renewable energy resources?
Damages to environment
People more aware that Non renewables will run out
Pressure from other countries
Car companies are producing electric cars as popularity increases
How is the use of renewables limited?
Money - very expensive to change
Space - where to put new power plants
Reliability
Politics - hard to change views
