Topic 1 - Energy Flashcards
What are the 8 different energy stores?
thermal
kinetic
gravitaional potential
elastic potential
chemical
magnetic
electrostatic
nuclear
What are the four ways that energy can be transferred?
Mechanically, electrically, heating , radiation
WHat is a closed system ?
a system where neither matter nor energy can enter or leave
the net change in the total energy of a closed system is always 0
Describe the energy transfers when boiling water in a kettle.
energy is transfered electrically to the thermal energy store of the kettles heating element which transfers energy by heating to the waters thermal energy store.
When is kinetic energy transfered/ used?
in moving objects
when an object speeds up , energy is transfered to it.
when it slows down , energy is transferred away .
What is the equation for kinetic energy ?
E = 1/2 m v ^2
energy = 1/2 mass x velocity ^2
When in an object is there more gravitational potential energy ?
When the object is lifted high
What is the equation for gravitiaional potential energy ?
E = mgh
energy = mass x gravity x height
What is the link between kinetic and gravitational potentai lenergy >
energy lost from G.P .E store = energy gained in kinetic store
When is energy transfered to an objects elastic potential energy store?
WHen an object is stretched or squashed
What is the equation for elastic potential energy ?
E = 1/2 k x e ^2
energy = 1/2 spring constant x extension ^2
What is specific heat capacity?
the amount of energy needed to raise the temperature of 1 kg of a substance by 1 degree celsius
What is the equation for specific heat capacity?
^E = mc^0
change in thermal energy = mass x specific heat capacity x temperatue change
Describe how you would carry out an investigation to work out the specific heat capacity of a substance.
1) get a block of your chosen material with two holes in it.
2) place a heater connected to a power supply in one of the holes.
3) connect an ammeter to the power supply.
4) measure the mass of the block of material then wrap it in insulating material to reduce the energy transferred from the block to the surroundings.
5) add a drop of water in the other hole and place your thermometer inside,
6) measure the initial temperature of the block and set the potential different of the power supply to 10v .
7) turn on the power supply and start a stop watch .
take readings of the temperature and current every minute for ten mins.
8) when enough readings are collected, turn off the power supply then calculate the power supplied to the ehater using p = vi
9) use results to calculate specific heat capacity.
What is the conservation of energy principle?
energy can be transferred usefully ,stored or dissipated ,but can never be created or destroyed
what are the two equations for power?
power = energy transfered / time
power = work done / time
What is conduction ?
the process where vibrating particles transfer energy to neighbouring particles.
What is thermal conductivity?
a measure of how quickly energy is transferred through a material through conduction
describe how energy is transferred through a solid by heating.
the energy is transferred to the thermal store of the object,
the energy is shared across the kinetic energy store of the particles in the object,
the particles in the parts of the object being heated vibrate more and colliede with eachother.
these collisions cause enery ti be transfered between the particle’s kinetic energy stores.
the process continues throughout the object untill the energy is transfered to the other side of the object .
What is convection?
where energetic particles move away from hotter to cooler regions.
what state of matter does convection happen in?
liquid or gas
Describe how convection works.
energy is trasnfered by heating to the thermal store of the liquid or gas.
it is then shared across the kinetic energy store of the gas or liquids particles.
the particles move faster and the space between the individual particles increases.
this causes the density of the region being heated to decrease
the warmer and less dense region will rise above the denser cooler region.
if there is a constant heat sourcee , a convection current can be created
Describe how radiators create convections currents.
energy is transferred from the radiator to the nearby air particles bu conduction.
the air by the radiator becomeswarmer and less dense.
the warm air rises and is replaced with cooler air.
the cooler air is then heated by the radiator.
at the same time, the previouslt heated airtransfers emergy to the surrounding .
it cools , beomces denser and sinks.
the cycle repeats cause a flow of air to cirsulate around the room
Wht are the two ways that we can reduce unwanted energy transfers ?
lubrication and insulation
