ENERGY Flashcards
What are the different types of energy stores?
Thermal
Kinetic
Gravitational potential
Elastic potential
Chemical
Magnetic
Electrostatic
Nuclear
How can energy be transferred?
By heating
By work done
What is an example of work done?
A person throws a ball
Energy transferred from the chemical energy store in the person’s arm to the kinetic energy store of the ball and arm
What happens when an object speeds up or slows down?
Energy is transferred to the kinetic energy store when an object speeds up and vice versa
What is a system?
An object or group of objects
How can energy be transferred?
Mechanically (force doing work)
Electrically (work done by moving charges)
Heating
What happens the higher an object is lifted?
The more energy is transferred to the gravitational potential energy store
What happens when an object falls?
Energy is transferred from its gravitational potential energy store to its kinetic energy store
What happens when there is air resistance on a falling object?
It causes energy to be transferred to other energy stores such as the thermal energy store
What is specific heat capacity?
The amount of energy needed to be transferred to a substances thermal energy store to increase its temperature by 1 degrees
What is the conservation of energy principle?
Energy can be transferred, stored or dissipated but can never be created or destoryed
Why is not all of the energy transferred useful?
There is wasted energy when the energy is being stored in a way that is not useful (e.g. thermal energy)
What is power?
The rate of energy transfer/doing work
What is conduction?
The process where vibrating particles transfer energy to neighbouring particles (shared across kinetic energy stores which vibrate the particles faster so they collide causing energy to be transferred)
What is thermal conductivity?
How quickly energy is transferred by conduction (to the thermal energy store across the kinetic energy store)
What is convection?
When energetic particles move away from hotter to cooler regions (only occurs in liquids and gases)
What are convection currents?
Warm air rises
Cool air sinks to replace rising air
How does lubrication reduce frictional forces?
For objects that are being rubbed together, lubricants can be used to reduce friction so not as much energy is transferred to wasted energy stores (thermal energy store)
How can you insulate your house?
Cavity walls (air gap in between which reduces the amount of energy transfer by conduction or filled with foam for convection)
Loft insulation reduce convection currents being created
Double-glazed windows (air gap to reduce conduction)
Draught excluders around doors and windows reduce convection
How can you improve the efficiency of energy transfers?
Insulating or lubricating objects
What are non-renewable energy resources?
These will all ‘run out’ one day
Reliable but damaging
Fossil fuels and nuclear fuel
(Coal, natural gas, oil)
What are renewable energy resources?
These will never run out
Not as damaging as non-renewables
Unreliable and not much energy
(Sun, wind, hydro-electricity, bio-fuel, tides, geothermal, waves)
What are the advantages of wind turbines?
No pollution
Minimal running costs
No permanent damage to landscape
What are the disadvantages of wind turbines?
Noisy
Expensive initial cost
Take up lots of space
Ugly/ruin view
Can’t increase power output when there is a demand
What are the advantages of solar cells?
No pollution
Good for charging batteries in objects that don’t use much electricity
Reliable if in a sunny country
Minimal running costs
What are the disadvantages of geothermal power?
Not many suitable locations for power plants
Cost of building a power plant is very high
What is geothermal energy?
Geothermal uses the heat that is naturally occurring below the surface of the Earth
Water can be pumped down into the Earth’s crust where it is heated up
The steam produced can be used to drive a turbine and generate electricity at the surface
What is hydro-electric power?
The water high up behind the dam contains gravitational potential energy
This is transferred to kinetic energy as the water rushes down through tubes inside the dam
The moving water drives electrical generators, which may be built inside the dam.
What are the advantages of hydro-electric power?
No pollution
Can provide an immediate response to an increased demand in electricity
Reliable (except in drought)
Minimal running costs
What are the disadvantages of hydro-electric power?
Expensive initial cost
Impacts the environment due to flooding of the valley (rotting vegetation) and loss of habitat
What are the advantages of wave power?
No pollution
Minimal running costs
What are the disadvantages of wave power?
Unreliable (waves rely on wind)
Disturbs seabed and habitats
Expensive initial cost
What are tidal barrages?
Big dams with turbines in them
Tide comes and the water is allowed through the turbines at a controlled speed
What are the advantages of tidal barrages?
No pollution
Reliable
Minimal running costs
What are the disadvantages of tidal barrages?
Spoils view
Prevents free access by boats
Alters habitats
What are biofuels?
Created from either plant products or animal dung
What are the advantages of bio fuels?
Carbon neutral
Reliable
What are the disadvantages of bio fuels?
Cannot respond to immediate energy demands
Causes deforestation
High cost
What happens when you burn coal and oil?
Sulphur dioxide is released which causes acid rain (sulphur is taken out before burning)
What environmental problems do non-renewables cause?
Acid rain
Oil spillages
Dangerous nuclear waste
Global warming
What are ways you can heat your home?
Burn natural gas / biofuel
SHC required practical
Initial temp
Turn on heater and timer and set to 10V
Take reading every 1 min for 10 mins
P = IV —>
E = Pt
Plot graph (temp and energy transfer)
SHC = change in E / change in temp / mass
What happens when thermal energy is increased during convection?
Increased kinetic energy
Particles get less dense
So it rises as it is less dense
What happens when thermal energy is decreased during convection?
Decreased kinetic energy
Particles get more dense
So it sinks as it is more dense
