P1 1/2/3 Energy Flashcards
state the equation for work done
work done (energy transferred) = force x distance
W (E) = F x s
(J) (N) (m)
-> 1 J/s is equal to 1 W
state the equation for electrical work
electrical work = potential diff x charge
E = V x Q
(J) (V) (C)
state the equation for gravitational potential energy
ΔGPE = mass x gravitational field strength x height
ΔEp = m x g x h
(J) (kg) (N/kg) (m)
describe the GP energy store
- energy stored in an object raised above ground
- when mass+ height of object and gravitational field strength increases, its store of GPE increases
state the equation for kinetic energy
KE = 1/2 x mass x velocity²
Ek = 1/2 x m x v²
(J) (kg) (m/s)
describe the kinetic energy store
- energy stored in a moving object
- transferred into the store when the object speeds up, transferred out when object slows down
- when mass+ speed of object increases, its store of kinetic energy increases
state the equation for elastic potential energy
elastic potential energy = 1/2 x spring constant x extension²
Ee = 1/2 x k x e²
(J) (N/m) (m)
describe the elastic potential energy store
- energy stored in an object that is stretched/ squashed
- the more it is stretched/ squashed, the greater its store of EPE
-> providing the object has not exceeded its limit of proportionality
name objects which store chemical energy
- foods
- muscles (transferred out when someone pushes something)
- batteries
state the equation for efficiency
useful energy output (J) / total energy input (J)
state the equation for power
power = energy transferred / time taken for transfer
P = E / t
(W) (J) (s)
state the gravitational field strength on earth
9.8N/kg
define internal energy
- energy in an object due to movement and position in a gravitational field
- sum of KE and GPE
name the energy stores (8)
Magnetic- object affected by magnetic field
Gravitational potential- position in a gravitational field/ height above ground
Electrostatic- object is electrically charged
Thermal- when object has high temp
Nuclear- energy released when atoms split/fuse
Elastic potential- when object is stretched/squashed
Chemical- when chemical reactions takes place
Kinetic- energy due to movement
name energy transfers (4)
work has been transferred by..
* heating
* radiation/ waves
* electric current
* work done by forces (eg. mechanical work by humans, against friction)
define mechanical work
the amount of energy that has been transferred by a force (Joules)
eg. chemical energy is transferred mechanically by work done by forces to the kinetic energy store of a ball (thrown upwards)+ the arm
define nuclear energy
energy released when atoms either split or fuse together
define dissipation
when energy is transferred to the thermal store of the surroundings as waste energy
state the use of lubrication and thermal insulation
- lubrication - use of oil/grease to reduce friction between two parts therefore reducing unwanted energy transfer as thermal energy
- insulation - using materials with low thermal conductivity to reduce unwanted energy transfer as thermal energy (loft insulation, triple-glazed windows)
describe fossil fuels, pros+cons
fuel is burned to heat water into steam -> steam turns turbines to power an electricity generator
/ low cost, reliable as readily available
X non-renewable, produce CO² which is a greenhouse gas that contributes to climate change, burnt coal causes acid rain
describe the effect of fossil fuels on global warming
- glaciers/ ice sheets melting- rising sea levels, loss of polar habitats
- rising sea levels- more flooding in low-lying coastal areas, submersion of coastal towns
- extreme weather, change in precipitation patterns
- carbon monoxide/ sulfur dioxide/ soot/ nitrogen oxide - affect human health, acid rain, smog, global dimming
describe nuclear fuel, pros+cons
fuel undergoes a nuclear reaction to release thermal energy -> heats water to steam -> steam turns turbines to power an electricity generator
/ generates a lot of energy per kg of fuel, reliable, doesn’t release greenhouse gases
X non-renewable, requires safety measures as radioactivity is dangerous, expensive construction+security costs (from tourists), produces radioactive waste
describe wind power, pros+cons
wind turns a turbine which powers an electricity generator
/ sustainable, no pollution, used in remote areas
X unreliable as no energy provided when it’s not windy+ turbines are turned off when too windy as they can break, considered ugly, noisy
describe solar power, pros+cons
thermal energy from sun is focused to boil water to steam in a power station / solar panels use thermal energy for heating / photocells convert light to electricity
/ sustainable, no pollution, excess energy from domestic solar panels can be sold back to energy producers, some used in remote areas
X unreliable as no energy produced at night or in bad weather, expensive, only used in desert countries, noisy, ruin landscape
describe hydroelectric power, pros+cons
build a dam, river flows over turbines to power generator
/ reliable, sustainable, easily controlled, no pollution
X requires flooding land, destroys local area+habitats, ugly structure
describe tidal power, pros+cons
turbine driven with tide movement to power generator
/ reliable, no pollution, sustainable
X ugly, dangerous for wildlife+damages habitats
describe biofuel, pros+cons
crops are burned for fuel to heat water to steam -> steam turns a turbine to power electricity generator
/ sustainable, reliable, renewable/ carbon neutral if plants are regrown - take in the CO² produced when burned, can use animal waste
X produces greenhouse gas, requires land for crops which reduces land available for food crops, using wood leads to deforestation
describe geothermal power, pros+cons
water is pumped underground to areas which are tectonically active -> water is boiled by heat of the earth -> steam turns turbines to power electricity generator
/ reliable, no pollution
X can only be used in volcanic areas
describe wave power, pros+cons
waves drive the turbine which powers the electricity generator
/ sustainable, no pollution
X unreliable as relies on strong waves, ugly, damages habitats
name the main uses of energy resources (3)
- transport: mainly oil fuels (petrol, diesel, kerosene), new biofuel or electrically-powered vehicles
- heating: mainly natural gas, wood/ coal/ oil burners, new electric heaters
- electricity generation: UK’s supply comes from many sources, mainly fossil fuels (gas/ coal), nuclear power, renewable sources (mainly wind/ biomass)
