Science - Physics - Energy - P1 Flashcards
state the 8 main energy stores
- kinetic
- magnetic
- internal (thermal)
- elastic potential
- gravitational potentiak
- nuclear
- electrostatic
- chemical
what is a magnetic energy store ?
the nergy store when attracting poles are pulled further apart and replling poles are pushed closer together
give examples of a magnetic energy store
fridge magnets, compasses, maglev trains which use magnetic levatation
what is an internal (thermal) energy store
the totel kinetic and potential energy of the particles in an object, in most cases this is the vibrations - also known as the kinetic energy - of particles. in hotter objects, particles have more kinetic energy and vibrate faster
give an example of an internal (thermal) energy store
human bodies, hot coffees, stoves - ice particles vibrate slower but still have energy
what is a chemical energy store ?
energy stored in chemical bonds, such as those between molecules
give an example of a chemical energy store
foods, muscles, electrical cells
what is a kinetic energy store ?
the energy of a moving object
give an example of a kinetic energy store
runners, buses, comets
what is an electrostatic energy store ?
energy stored when repelling objects have been moved closer together or attracting objects have been pulled further apart
give an exampke of an electrostatic energy store
thunderclouds
what is elastic potential energy store ?
the energy stored when an object is stretched or squashed
give an example of an elastic energy store
compressed springs, inflated ballons
what is gravitational potential energy store ?
the energy of an object at height
give an example of a gravitational potential energy stoe
kites, aeroplanes
what is a nuclear energy store ?
the energy stored in the nucleus of an atom
give an example of a nuclear energy store
nuclear reactors
give an example of an energy transfer when bringing water to the boil in a kettle
electricity through the kettle increases the internal energy of the element which in turn increases the internal (thermal) energy of the water which increases the temperature of the water
how is energy transferred ?
by one of four types of enrgy transfer:
mechanical work
electrical work
heating
radiation
what is mechanical work ?
a force moving an object through a distance
what is electrical work ?
charges moving due to potential difference
what is heating ?
temperature difference caused electrically or by a chemical reaction
what is radiation ?
energy tranferred as a wave, eg light and infrared - light radiation and infrared radiation are emitted from the sun
what does dissipated mean ?
often referred to as ‘wasted’ energy
in a mechanical system, energy is dissipated when two surfaces rub together. Work is done against friction which causes heating of the two surfaces - so the internal energy of the surfaces increases, what can be done to reduce this ?
adding a lubricant can reduce friction - less heat is wasted
how is energy dissipated in a tumble dryer ?
energy is dissipated by sound waves
how is energy used usefully in a tumble dryer ?
electical work is transferred into thermal energy, which is used to help dry clothes
what is the conservation of energy ?
energy can be transferred, usefully stored or dissipated but it can never be created or destroyed
give an example of the conservation of energy in a skydiver
when a skydiver jumps out of a plane, he loses gravitational energy as his height decreases but gains kinetic enrgy as he gains speed
how do you calculate kinetic energy ?
kinetic energy = 1/2 X mass X speed squared
what is kinetic energy (Ek) measured in ?
joules
how do you calculate elastic potential energy ?
1/2 X spring constant X extension squared
what is elastic potential energy (Ee) measured in ?
joules
how do you calaculate gravitational potential energy ?
mass X gravitational field strenght X strength X height
what is gravitational field strength (Ep) measured in ?
joules
what is a force ?
a push or pull
what is energy ?
the capacity for doing work
what is work done ?
the measure of energy transfer when a force moves an object through as distance
what does the amount of work done when a force acts on a body depend on ?
- size of force acting on the object
- distance throuugh which the force causes the body to move in the direction of the force
how do you calculate work done ?
force X distance
what is work done measured in ?
joules
what is power ?
the amount of energy that is transferred per second
how do you calculate power ?
work done / time
what is power measured in ?
watts
what is efficiency ?
how good a device is at transferring useful energy input into useful enrygy output
how do you calaculate efficiency ?
useful energy transferred/ total energy supplied X100
can you have an efficiency rate greater than 100% ?
no, as that would mean energy is being created which goes against the law of conservation of energy
how is energy useful in an electric kettle ?
energy that heats the water
how is energy wasted in an electric kettle ?
thermal energy heating the kettle, infrared radiation lost to surroundings
how is energy wasted in an electric kettle ?
thermal energy heating the kettle, infrared radiation lost to surroundings
how is energy useful in a light bulb ?
light radiation given out by the hot filament
how is energy wasted in a light bulb ?
infrared radiation lost to surroundings
name the main energy resources
fossil fuels, nuclear fuel, bio-fuel, wind, hydroelectricity, geothermal, tidal, water waves and the Sun
what is an energy resource ?
a useful supply or store of energy
where is energy needed ?
homes - cooking
public places - hospitals + schools for machinery, heating
transport - buses, cars need a fuel source to move
how can producing and distributing energy harm the environment?
releasing energy from some stores causes pollution and harmful waste products, burning fossil fuels releases carbon dioxide, adding to the greenhouse effect, and sulphur dioxide which causes acid rain
what is renewable energy ?
energy soures that are replenished and not exhausted, eg solar power
what does non - renewable mean ?
it will eventually be used up
state 2 renewable energy sources
wind, bio-fuel
state 2 non-renewable energy sources
nuclear feuls, fossil fuels
what are the 3 ways energy is transmitted ?
conduction
convection
radiation
what is a conductor ?
a material that allows thermal energy to be transmitted through it easily
what is an insulator ?
a material that does not allow charge or heat to pass through it easily
what is thermal conductivity ?
a measure of how wella material conducts energy when it’s heated
state how to carry out the exeriment to investigate the effectiveness of different materials as thermal insulators
- place a small beaker into a larger beaker.
- fill the small beaker with hot water from a kettle.
- put a piece of cardboard over the beakers as a lid. The lid should have a hole suitable for a thermometer.
-place a thermometer into the smaller beaker through the hole. - record the temperature of the water in the small beaker and start the stopwatch.
- record the temperature of the water every 2 minutes for 20 minutes.
- repeat steps 1-6, each time packing the space between the large beaker and small beaker with the chosen insulating material.
- plot a graph of temperature (y-axis) against time (x-axis).
state 2 hazards of the required practicals
- boiling water -scald skin - do not overfill kettle
- knocking over beaker - scald skin - place beaker away from the edge of the desk
state how to carry out the experiment investigating the effectiveness of different thicknesses of thermal insulators
- wrap a sheet of newspaper around a 100 ml beaker.
- fill the beaker with hot water from a kettle.
- put a piece of cardboard over the beaker as a lid. The lid should have a hole suitable for a thermometer.
- place a thermometer into the beaker through the hole.
- record the temperature of the water in the beaker and start the stopwatch.
- record the temperature of the water every 2 minutes for 20 minutes.
- repeat steps 1-6, each time adding another layer of newspaper around the beaker until there are 10 layers of newspaper wrapped around the beaker.
- plot graphs of temperature against time
what is temperature ?
a measure of the average kinetic energy of the molecules
different materials require different amounts of energy to change temperature, the amount of energy needed depends on what ?
- mass of the material
- substance of the material
- the desired temperature change
what is specific heat capacity ?
the amount of energy needed to raise the temperature of 1kg substance by 1 degrees C
how do you calaculate the change in thermal energy ?
mass X specific heat capacity X temperature change
explain how to carry out the experiment where you are investigating measuring the specific heat capacity of a material
- place the immersion heater into the central hole at the top of the block.
- place the thermometer into the smaller hole and put a couple of drops of oil into the hole to make sure the thermometer is surrounded by hot material.
- fully insulate the block by wrapping it loosely with cotton wool.
- record the temperature of the block.
- connect the heater to the power supply and turn it off after ten minutes.
- after ten minutes the temperature will still rise even though the heater has been turned off and then it will begin to cool. Record the highest temperature that it reaches and calculate the temperature rise during the experiment.
how do you calaculate energy transferred ?
potential distance X current X time
evalute the experiment investigating the specific heat capacity of a material
- not all of the heat from the immersion heater will be heating up the aluminium block, some will be lost to the surroundings
- more energy has been transferred than is needed for the block alone as some is transferred to the surroundings,this causes the calculated specific heat capacity to be higher than for 1 kg of aluminium alone
state a hazard for investigating the specific heat capacaity of a material
hot immersions heater and a sample material - burnt skin - do not touch when switched on
what is conduction ?
the process by which vibrating particles transfer energy to neighbouring particles
which state does conduction most commonly occur in ?
solids
what is thermal conductivity ?
a measure of how quickly energy is transferred through a material
what can materials with high thermal conductivity do ?
transfer energy between their particles quickly
what are materials with high thermal conductivity known as ?
thermal conductors
what are materials with a low thermal conductivity known as ?
thermal insulators
what is convection ?
where energetic particles move away from hotter to cooler regions
which state can convection happen in most ?
liquids and gases
why does convection happen in liquids or gases ?
their particles are able to move around rather than vibrate in place so the space between individual particles increase causing the density of the region being heated to decrease
give examples of thermal insulators in the home ?
cavity walls
loft insulation
double glazing
draught proofing
hot water tank jacket
thick curtains
how do cavity walls work as thermal insulators ?
they are made up of an inner and outer wall with an air gap in the middle
the air gap reduces amount of energy transferred by conduction through the walls as air is an insulator
how does loft insulation work as a thermal insulator ?
fibreglass (insulating material) wool being laid out across the whole loft reduces conduction to the attic space as the material are insulators
