energy Flashcards
what are the different energy stores?
thermal, kinetic, gravitational, potential, elastic, chemicals, magnetic, electrostatic, nuclear
whats a system?
the object you’re interested in
when can energy transfer happen?
during heating or when work is being done
when can work be done?
when current flows or by a force moving an object
what is kinetic energy?
anything moving, falling.
what is gravitational potential energy?
any raised object
what is elastic potential energy?
stretching
what is specific latent heat?
how hard it is to heat something up, amount of energy required to raise 1kg by 1.
how to investigate specific heat capacities?
block of material with 2 holes
measure block mass
wrap in insulating layer
insert themometer and heater
measure initial temp
turn on power supply + stop watch
take reading every minute
what is the conservation of energy?
energy can be transferred usefully, stored or dissipated but can never be created or destroyed.
what is power?
rate of energy transfer, measured in watts, 1 joule of energy per s
what makes a powerful machine?
exerts more energy in smallest time period
what is conduction?
vibrating particles transferring energy to neighbours.
what is convection?
liquids or gases, heat = particles move faster , density decreases
what does a radiator do? (convention current)
transfer energy to near by particles, becomes less dense, rise up then replaced by heavier particles and same repeats.
how do you reduce energy loss?
lubrication or thermal insulation
what is insulation?
thick walls made of low thermal conductivity, double glazed windows
what do lubricants do?
reduce friction
how do you investigate effectiveness of materials as thermal insulators?
boil water, pour some into sealable container.
measure mass of water in container.
seal and leave for 5 minutes
remove and measure final temperature
pour away water and allow container to cool to room temperature.
repeat with different materials
can investigate with different thickness
what does efficiency =?
useful output over total output.
what is the only thing thats 100% efficient.
except electrical heaters as everything is converted to thermal energy.
what are examples of non-renewable materials?
coal, oil and gas. they are natural, underground for millions of years
what are exampled of renewable materials?
solar and wind, never run out, unreliable.
benefits of wind turbines?
no pollution, no permanent damage.
disadvantages of wind turbines?
noisy, spoilt the view, expensive, take up lots of land.
benefits and disadvantages of solar power?
no pollution but is very expensive and cant increase power output to meet demands.
disadvantages of geothermal power? (slow decay of radioactive elements)
expensive to build compared to amount of energy returned, not many suitable locations for it
benefits and disadvantages of hydroelectric power? ( flooding valley by building a dam)
releases CO2 and methane, loss of habitat, initial high costs but no fuel costs
evaluate wave power?
need lots of turbines, no pollution, fairly unreliable, high initial costs
evaluate tidal barrages?
no pollution, reliable, initial high costs.
what are biofuels?
renewable, plants or animal dung.
what are biofuels used for? evaluate them.
burnt for electricity, reliable, cant respond to immidiate demand.
evaluate non-renewable energy?
enough to meet current demand, running out, costs arent expensive.
Releases c02, sulfur dioxide (acid rain)
coal mining ruins landscape
nuclear waste= dangerous
