energy topic Flashcards
name all the energy stores
- thermal energy
- kinetic energy
- gravitational potential
- elastic potential
- chemical energy
- magnetic energy
- electrostatic energy
- nuclear energy
what is energy measured in?
Joules(J)
gravitational potential energy
mass x gravity x height
kinetic energey
0.5 x mass x (velocity)^2
elastic potential energy
0.5 x spring constant x (extension)^2
hook’s law
the force required to stretch an elastic object such as a metal spring is directly proportional to the extension of the spring.
work done
force x distance
power
the rate at which energy is transfered
efficiency def
a measure of how much energy is transferred usefully in a system
efficiency equ
useful energy output/ total energy input
or
useful power output/ total power input
what is solar power
works by converting light from the sun into electricity
solar power advantages
- pollution free and emits no green house gases
- reduces dependence on fossil fuels
- virtually no maintenance
- can be installed anywhere
solar power disadvantages
- needs a lot of space
- on cloudy days they produce little energy
- lower production in winter months
- usually used to produce energy on a small scale
solar power price
initial cost is high but after that the energy is free and running cost is almost nil
what is geothermal power
uses energy from underground thermal energy stores
geothermal advantages
- reliable with very few environmental problems
- 30%-60% savings on heating and 25%-50% savings on cooking
geothermal disadvantage
- only possible in volcanic areas
- large scale geothermal power plants are dangerous to the earths surface
- the amount to build is high compared to the energy produces
how does geothermal energy work
cold water is pumped down deep into the ground where it turns into steam. then the steam in pumped back up into turbines that generate electricity
what is hydroelectric power
is a dorm of energy that harnesses the power of water in motion
how does hydroelectric power work
at hydropower plants water flows through a pipe, or penstock( controlling or directing the flow of water), then pushes against and turns blades in a turbine to spin a generator to produce electricity
hydroelectric power advantages
- it can provide immediate response to increase demand for electricity
- there is no problem with reliability except for in times of a drought
hydroelectric power disadvantages
- it von disrupt wildlife habitat
hydroelectric costs
initial costs are high, but there are no fuel costs and minimal running costs
how does wind power work
each turbine has a generator inside it. the rotating blades turn the generator to produce energy
wind power advantages
- there is no pollution except when they are manufactured
- it is cost effective
- no permanent damage to landscape
wind power disadvantages
- they can be very noisy
- it would take 1500 wind turbines to replace one coal fuel power station
- ugly
wind power costs
the initial costs are quite high but there are no fuel costs and minimal running costs
what is wave power
is where air is forced into a generator by the waves
wave power advantages
- there is no pollution
wave power disadvantages
- disturbing sea bed and ruining habitats
- fairy unreliable since waves tend to die out when wind drops
wave power costs
the initial costs are high but there are no fuel costs and minimal running costs
what is tidal energy
tides are used lots of ways to generate electricity. the most common being tidal barrage
was is a tidal barrage
is a big do
tidal energy advantages
- there is no pollution
- the tides are pretty reliable in the sense they will happen twice a day without fail
tidal energy disadvantages
- they prevent free access by boats
- spoil view
- alter habitats
tidal energy costs
initial costs are moderate, high but there are no fuel costs and minimal running costs
what is biofuel
is any fuel that is derived from biomass
biofuel advantages
- efficient fuel
- it is easy to source
- reduces dependence on foreign aid
biofuel disadvantages
- industrial pollution
- shortage of food
biofuel costs
quite expensive
conduction
the process where vibrating particles transfer energy to neighbouring particles
convection
is where energetic particles move away from hotter to cooler regions
specific heat capacity
the amount of energy required to raise 1Kg of a substance by 1 degree C
change in thermal energy
mass x specific heat capacity x temp change
density
mass/volume
thermal energy store
the total energy of an object due to the kinetic energy of its atoms and/or molecules depending on its mass
temperature
a measure of the average kinetic energy of molecules
specific latent heat of fusion
is the energy required to convert 1kg of a substance from a solid to a liquid or from liquid to solid without
a change in temperature
specific latent heat of vaporisation
is the energy required to convert 1kg of a substance from liquid to gas or vies versa without changing the temperature
latent heat
energy/mass
