P1 Flashcards
types of energy
kinetic
thermal
electric
gravitational
chemical
elastic
magnetic
nuclear
what happens when an object falls?
It gains speed and its store of gravitational potential energy decreases and its kinetic energy store increases
Friction
work done to overcome friction is transferred as energy to the thermal energy stores of the objects that rub together and the surroundings
gravitational potential energy
gpe store of objects increase when moving upwards and decrease when moving downwards, because work is done on it to overcome gravitational force
energy dissipation
- wasted energy is transferred to the surroundings which become warmer
- as energy dissipates it gets less and less useful
How can machines be made more efficient?
Machines can be made more efficient by reducing the energy they waste by lubricating them to reduce friction between parts.
conductivity
- metals are the best conductors of energy
- non metals are the best insulators
- the higher the thermal conductivity the higher the rate of energy transfer
- the thicker the insulating material the lower rate of energy transfer through it
heat capacity
measures how much heat is needed to raise an objects temperature by 1 degree celsius
specific heat capacity
the amount of heat energy needed to raise the temperature of 1kg by 1 degree celsius
infrared radiation
- the higher the temperature of an object, the more infrared radiation it emits
- an object that has a constant temperature emits radiation across a continuous range of wavelengths
blackbody radiation
radiation emitted by a body that absorbs all the radiation incident on it
biofuels
biofuels are renewable sources of energy such as methane and ethanal which can be used to generate electricity.
non renewable energy sources
- coal, oil, gas and nuclear
- cheap, reliable
- will run out, pollution
renewable energy sources
- wind power, solar panels, tidal power
conduction
the heat is passed on by collision of particles
convection
the heat is passed on by fluid expanding, rising and taking the heat with it
insulating materials
Electrons are transferred when objects
- become positively charged when rubbed lose electrons
- become negatively charged when rubbed gain electrons
series circuit
- current the same in each component
- adding more resistors increases total resistance because current is reduced
parallel circuit
- total current is sum of currents through all components
- the bigger resistant of component the smaller the current passing through
- more resistors decrease resistance because total current is increased
internal energy
- when substance is heated its temperature rises the kinetic energy of particles increase
- if it melts or boils the potential energy of particles increase
- pressure of gas on surface is caused by particles of gas hitting the surface
pressure
- if temperature of gas in a sealed container is increased the pressure increases because molecules move faster hitting the surface with more force
wires
- green/yellow = earth wire
- brown = live wire
- blue = neutral wire
Fuse w earth wire protect from electricution
radioactive decay
radioactive substances are unstable and continuously give out radiation.
radioactivity
decay that happens with a certain probability
alpha radiation
when an atom decays into a new type of atom and emits an alpha particle
2 protons and 2 neutrons
Beta radiation
when a neutron turns into a proton and electron
Gamma radiation
high energy light with high frequency and short wavelength.
Half life of an atom
time taken for half of the radioisotopes in a sample to decay.
