y9 revision 2 Flashcards
list the 8 energy stores
thermal energy, chemical energy, nuclear energy, kinetic energy, elastic potential energy, magnetic energy, electrostatic energy, gravitational potential energy
name the four ways in which energy can be transferred
electrical, radiation, mechanical, heating
what is a closed system
where neither matter nor energy can enter or leave. the net charge in the total energy of closed system is always zero
what is the unit of energy?
joules (j)
what is gravitational potential energy equation, with units?
Ep= mgh
GPE = joules (j)
mass = kilograms (kg
height - metres (m)
what is the kinetic energy equation, with units?
Ek = 0.5 mv^2 KE = joules (j) mass = kilograms (kg) speed = metres per second (m/s)
what is the law of conservation of energy?
energy is not created or destroyed but transferred from one store to another
what is the equation of power? with units
P = E/t Power = watts (w) Energy = joules (j) Time = seconds (s)
where is heat lost in a house?
windows, roof, walls, doors and floors
what is the efficiency equation?
Efficiency = useful energy/ total energy Efficiency = useful power/ total power
define the term power
the rate of transfer of energy
describe the energy transfer when a moving car slows down
energy is transferred mechanically from the kinetic store of the car to the thermal store of the surrounding
some energy is dissipated to the thermal store of the surrounding
describe the energy transfer when electric kettle is used an elastic band
the electric current in a kettle transfers energy to the heating element’s thermal store of the surroundings
describe the energy transfer when battery powered toy car is used
energy is transferred electrically from chemical store of the battery to the kinetic store of the toy car - some of the energy is dissipated to the thermal store of the surrounding
describe the energy transfer when a falling apple hits the ground
energy is transferred from kinetic store of the apple and dissipated to the thermal store of surroundings by sound waves
name the unit that represents one joule transferred per second
watts (w)
what is work done?
energy transferred when force moves an object
what would happen to the kinetic energy of the mass of the object double, but the speed stayed the same?
the kinetic energy would double
what would happen to the kinetic energy of the speed of the object double, but the mass of the object stayed the same?
the kinetic energy would be quadruple
what is the elastic potential energy equation, with units?
Ee= 0.5 ke^2
Elastic potential energy = joules (j)
spring constant = newton per meter (N/m)
extension = meter (m)
what is meant by the term extension and spring constant?
extension is the charge in the length of the spring constant in the stiffness of the spring
what is the meaning of specific heat capacity?
the specific heat capacity of a substance is the amount of energy required to raise the temperature of one kilogram of the substance by one degree Celsius
what is the equation for specific heat capacity? with units
△E = mc △0 (line in the 0) change in thermal energy, △E, in joules, J mass = kilograms, kg specific heat capacity, J/kg °C temperate change = °C
what is the dependent, independent and control variable for the specific heat capacity practical?
Independent variable is the energy transfer
dependent variable is the temperature change
control variable are insulation (quantity and type), same heater, same method of transferring energy
describe the ways to reduce heat loss in a house
windows ~ double glazing, air gap between the two sheets of glass to prevent energy transfer by conduction
thick curtains ~ the cloth over the window creates air gap between the room and the window which reduces the energy transfer by conduction
roof ~ loft insulation, thick layer of fibreglass reduces conduction as it traps pockets of air
walls ~ cavity wall insulation, the air gap reduces the amount of energy transferred by conduction through the wall
doors ~ draught excluders, stops draught blowing in and out and reduces energy transfer by convection
name the renewable and non - renewable resources of energy?
non - renewable ~ coal, oil , gas and nuclear
renewable ~ solar energy, wind turbine, waves, geothermal, tidal, hydroelectric, biomass
list the advantages of fossil fuels
readily available
enough resource to meet the current demand. reliable source of energy
cheap to extract and use
list the disadvantages fossil fuels
releases carbon dioxide into the atmosphere which contributes to global warming
releases sulphur dioxide into the atmosphere which causes acid rain
going to run out
list the advantages of nuclear power
lots of energy releases from a small amount of fuel
reliable can control supply to match the demand
enough fuel available to meet the current demand
no polluting gases
list the disadvantages of nuclear power
waste is dangerous and difficult and expensive to deal with
expensive initial set up
expensive to shut down and to run
list the advantages of solar energy
can be used in remote places
no polluting gases
no waste products
very low running costs
list the disadvantages of solar energy
unreliable
cannot control supply
initial set up expensive
cannot be used on a large scale
list the advantages of wind power
clean renewable source of energy
relatively low set up cost pre unit of electricity generated
large potential both on and offshore in the UK
wind farms tend to produce more electricity in the winter when demand is also higher
list the disadvantages of wind power
wind power is not reliable, if wind is light then no power generated
some people do not like the look of them
potentially harm some birds
some people do not want them near their home due to visual impact and noise
list the advantages of tidal power
now polluting gases no waste products reliable can produce large amounts of electricity low running cost no fuel costs
list the disadvantages of tidal power
can harm marine habitat initial set up expensive cannot increase supply when needed amount of energy varies on time of month hazard for boats
list the the advantages of wave turbines
no polluting gases produced
no waste products
low running cost
no fuel cost
list the advantages of wave turbines
unreliable, dependent on weather cannot control supply initial set up expensive can harm marine habitats hazard for boats cannot be used on a large scale
list the advantages of geothermal energy
clean and renewable
no air pollution or carbon dioxide production
minimal damage to the environment
constant source of energy
list the disadvantages of geothermal energy
only a few places on Earth are suitable where the Earth’s core is close enough to the surface to make use of the geothermal energy
Expensive and difficult to drill deep into the ground
list the advantages of biofuels
carbon neutral fuel as carbon dioxide is absorbed when growing so it does not add to the overall carbon dioxide in the atmosphere
can be used to replace the burning of fossil fuels like coal in power stations
list the disadvantages of biofuels
emits carbon dioxide and soot when burnt
bulky to transport requiring large volumes for the same energy output compared to fossil fuels
requires energy to transport and process
