P1-Energy and Energy resources Flashcards
What is a system?
An object or group of objects
What are the energy stores ?
magnetic Thermal chemical kinetic electrostatic elastic potential gravitational potential Nuclear
Wha happens to energy when a system changes?
Moves to a different store
Energy stores for when an object is projected upwards?
Kinetic energy is used to throw the ball up , then it slows down and energy is stored to Gravitational potential energy store , then as it falls it moves to kinetic energy . When it hits the ground it moves from kinetic to sound and thermal .
How is energy trasnferred
By heating , waves , electric current or a force when an object moves.
What happens when an object hits the ground (energy stores)?
Some or all of the energy is transferred to the surroundings. The thermal energy store of the surroundings increases and also sound waves are made.
Why can be done to energy ?
Stored or dissipiated
What cannot be done to energy?
Destroy it.
What is a closed system?
A system where no energy transfers take place out or in the energy stores of the system
Can energy still be transferred in close systems?
Yes, but the total energy is the same as the total energy after as was before.
How energy transfers when boiling water in a kettle?
- water is the system . Energy is transferred to the water from heating. The temperature of the water rises and thermal energy store rises.
- electrical energy in the kettle is transferred to thermal energy store in the kettles heating element
What is work done?
When a force causes an object to move work is done to the object. Work done is basically another way of describing energy transfer.
Energy transfers when a person throws a ball upwards?
Chemicals stores from the persons arm to kinetic energy store of the ball and arm.
Energy transfers of a vehicle slowing down?
Friction between cars breaks and wheels does work as it slows down . It causes an energy transfer from wheels kinetic energy store to thermal energy of the surroundings
Equations for work done?
Work done = force x distance
W=F s
Work done , W , joules
Force , f , newtons
Distance , s , metres
Energy transfer of a collision between a car and stationary object?
Kinetic energy to other energy store . Elastic potential and thermal energy stores of an object and car body. Some also might be transferred by sound energy.
How to calculate kinetic energy?
Kinetic energy =0.5 x mass x (speed)^2
Ek = 1/2 M v^2
Kinetic energy , Ek , joules
Mass, m , kilograms
Speed , v , metres per second
How gravitation potential energy is stored?
Lifting an object in a gravitational field requires work . So the higher the object the more gravitational potential energy. there is
What is the equations for gravitational potential energy?
Gpe= mass x gravitational field strength x height
Ep=m g h
Gpe, Ep, joules
Mass, m, kilograms
Gravitation field strength, g, newtons per kilogram
Height, h, metres
What causes elastic potential energy stores?
Stretching or squashing an object, assuming the limit of proportionality has not been exceeded
Equation for elastic potential energy?
Elastic potential energy= 0.5x spring constant x extension ^2
Ee= 1/2 k e^2
Elastic potential energy , Ee, joules
Spring constant , k , newtons per metre
Extension , e, metres
What is one joule to a newton metre?
1 joule is equal to one newton metre
When work is done against frictional forces acting on an object what happens?
Rise in temperature of the object.
Equation for change in thermal energy?
Mass x specific heat capacity x temperature change.
Change in E= m c change in Ø
Change in thermal energy store, joules
Mass, m , kg
Specific heat capacity, c , j/kg degrees celsius
Temperature change, degrees celsius
What is the specific heat capacity of a substance?
Amount of energy required ro rase temperature of one kilogram of the substance by one degree . It basically means how difficult it is to heat something up
What does the increase in temperature of a substance depend on?
- mass
- type of material
- energy input to the system
What is power?
Rate at which energy is transferred or rate at which work is done.
How to calculate power ?
Power = (work done or energy transferred )/time P= E or W/t
Power , p , watts
Energy transferred, E , joules
Time, t , seconds
Work done , w , joules
What is one joule equal to in watts?
1 joule per second = 1 watt
How power can be presented in two cars that are identical except for in heir engine power?
Both cars race the same distance along a straight race track . The car with more powerful engine will reach finish line faster than other. It will transfer the same amount of energy but over less time.
What happens to energy when stores are changed?
Most goes to store that is transferred too but some is always dissipated.
What is dissipated energy?
Wasted energy , because it is being stored in a way that is not useful , usually it is heat energy. It is spread out in the surroundings
Most wasteful force?
Friction
Examples of energy transfers in a closed system?
Cold spoon dropped into an insulated flask of hot soup , which is sealed. Spoon an soup form a closed system as we can assume the flask is a perfect insulator. Energy from the thermal energy store of the soup to the useless thermal energy store of the spoon , causing the soup to cook down slightly. Energy transfers have happened but no energy has left the system.
Ways of preventing useless energy transfers?
- lubrication
- thermal insulation
What does lubrication do?
Reduce friction.
What is thermal insulation?
Preventing heat energy from escaping.
Ways of thermal insulation?
- thick walls with a low thermal conductivity
- cavity walls made up of inner and outer walls with air gap in middle. Air gap reduces amount of energy transferred by conduction through the walls. Reduces energy transfers by convection
- loft insulation can reduce convection currents
- double glazed windows work like cavity walls
- draught excluders
What are convection currents?
A cycle where air particles are constantly being heated , rising , cooling and then sinking.
How does a high thermal conductivity affect the rate of energy transfer by conduction?
Increases the rate. high thermal conductivity mean energy transfers of particles will happen at a faster rate.
How can efficiency be calculated?
Efficiency=
Useful power output /total power input
Useful output energy transfer/total input energy transfer
What are the main resources available for use on earth?
- fossil fuels(coal, oil and gas)
- Nuclear fuel
- biofuel
- wind
- hydroelectricity
- geothermal
- the tides
- sun and water waves
What is a renewable energy resource?
Resource that can be replenished and will never run out. Most damage the environment but in less ways than non renewables. Unreliable ,some depend on weather.
Renewable energy stores?
- sun
- wind
- waves
- Hydroelectricity
- biofuel
- tides
- geothermal
How are fossil fuels formed?
Underground over millions of years
What is a non renewable resource?
A resource that will eventually run out and they damage the environemnt
Examples of non renewable resources?
- coal
- oil
- natural gas
Non renewable energy resources for transportation?
- petrol and diesel
- use fuel created from oil
- coal used for old fashioned steam trains
Renewable energy resources for transport?
Vehicles that run on pure biofuels or a mix of a biofuel and petrol
Non renewable resources for heating?
- natural gas in homes
- heat water
- pumped into radiators
- coal
- electric heaters , uses energy generated from non renewable resources
Renewable sources of energy to heat?
- geothermal heat pump uses geothermal energy resources to heat buildings
- solar water heaters work by using the sun to heat water which is then pumped into radiators in the building
- burning biofuels or electricity generated from renewable resources
What was is wind power ?
- wind turbines generate it , as the wind turns the generator producing electricity
- no pollution
- spoil view, and need a-lot
- can be very noisy
- reliant on wind
- initial costs are quite high but no running costs and extra fuel costs
- no permanent damage to the landscape
What is solar energy?
- generate electricity directly by sunlight
- used to charge batteries
- used in remote places and powers electric road signs and satellites
- no pollution
- in sunny countries , reliant on sun
- initial costs are high , but no other costs
- used to generate electricity on a smaller scale
What is geothermal power?
- possible in volcanic or where hot rocks lie near the surface.
- source is from slow decay of various radioactive elements including uranium , deep inside the earth.
- reliable and does little damage to the environment
- can be used to generate electricity or to heat buildings directly
- aren’t many suitable locations for power plants and the cost of building a power plant is often high compared to energy produced
What is hydroelectricity ?
- usually requires flooding of a valley by building a dam . Water is allowed out through turbines
- no pollution
- bad impact on the environment due to valley flooding. Possible loss of habitat for some species .
- can provide immediate response to an increase in demand for electricity
- reliant on water supply, some countries suffer from droughts
- initial costs are high but no fuel costs and minimal running costs
- useful way to generate electricity on a small scale.
What is wave power ?
- lots of small wave powered turbines located around coast , like wind power , moving turbines are connected to a generator .
- no pollution
- disturb seabed and marine habitat
- spoil view
- Hazard to boats
- fairly unreliable , since waves tend to die out when wind drops
- initial costs are high , no fuel costs and minimal running costs
- unlikely to provide energy on a large scale , can be very useful on small islands
What is tidal power?
- build tidal barrages , which are big dams built across river estuaries with turbines in them. As tide comes in fills up estuary . The water is then allowed out through turbines at a controlled speed.
- tides produced by gravitational pull of sun and moon
- no pollution
- prevent free access to boats, spoil view and alter habitat of wildlife
- pretty reliable , happens twice a day without fail and always at predicted heights.
- height of tide is variable so lower tides will provide significantly less energy than bigger.
- initial costs are high , no fuel costs and minimum running costs
- has potential to produce a significant amount of energy
What are biofuels ?
- renewable energy resources created from plants or animal dung
- can be burnt to produce electricity or run are like fossil fuels
- carbon neutral
- reliable as crops take short time to grow. Cannot respond to immediate demands though, so biofuels are immediacy produced and stored
- very high costs to refine
- some regions deforestation has taken place to make room for biofuels resulting in a loss of species and habitats. Decay and burning also increased co2 emissions
Features of non renewable resources ?
- reliable. Stored and power plants have extracted lots so can react quickly to demand
- fuels are running out.
- set up costs are high . Running costs are not . Fuel extraction costs are fairly low so it is a cost effective way to produce energy
How do non renewable resources create environmental problems?
- release co2 into atmosphere when burnt. Contributes to global warming
- Bruin’s coal and oil can release soulful dioxide which causes acid rain
- fuel can be cleaned by taking sulphur out
- coal mining messes up landscape
- oil spillages cause serious problems affecting mammals and birds living around the sea
- nuclear power is clean , but waste is dangerous
- nuclear power is expensive and has always a risk of disaster