ch1 Flashcards
what is the conservation of energy
energy cannot be created or destroyed, it can be stored or transferred , it can be useful or wasted
how can energy be transferred
- by heating
- mechanically (by force)
- electrically
- radiation
what is dissipated
spread out to the surroundings
what is work done
the amount of energy transferred when a force causes something to be dissipated or move
what is kinetic energy abd some examples
the energy of a moving object e.g runners , busses
what is magnetic every and down examples
the energy stored when repelling poles have been pushed closer together or when attracting poles have been pulled further apart
e.g compasses, fridge magnets
what is thermal energy and some examples
the total kinetic and potential energy of the particles in an object- in most cases this is the vibrations . i’m hotter objects the particles have more internal energy and vibrate faster
e.g human bodies, hot coffees, stove or hobs
what is gravitation potential energy and some examples
the energy of an object at height
e.g planes, kites
what is chemical energy and some examples
the energy stored in chemical bonds such as those between molecules
e.g foods , muscles , batteries
what is nuclear energy and how can it b released and what are some examples of nuclear energy
the energy stored in the nucleus of an atom it can be released by radioactive decay
e.g nuclear power station or nuclear reactors
what is elastic energy and some examples
the energy stored when an object is stretched or squashed
e.g springs, inflated balloons, drawn catapults
formula for work done
work done = force x distance
force measured in newton’s
distance measures in meters
what is energy measured in
Joules
what is gravitational field strength
the force that pulls everything to the center of the earth (9.8N/kg)
what does work done when an object moves up or down depend on
- how far it has moved vertically
- it’s weight
what is weight
weight is the force of attraction to the center of the earth
what is mass
the amount of matter
what is mass measured in
KG
what is weight measured in
newton’s
what is normally dissipated (2)
light radiation sound radiation
what is power measured in
watts
definition of power
power is that RATE at which energy is used or supplied. the more powerful an appliance is,the faster the rate at which is transfers energy
how many watts in 1KW
1000 Watts
what is 1 watt equal to in transferring joules
1 watt is = to the rate of transferring 1 joules of energy in one second
what is specific heat capacity
amount of thermal energy needed to raise the temperature of 1KG if a substance by 1 degrees c
what materials are good insulators
good insulators are materials that have low thermal conductivity so energy transfer through them is as low as possible
energy transfer per second through material depends on?
- temp difference across the material
- thickness of material
- thermal conductivity of metal
to reduce the energy transfer as much as possible the:
- thermal conductivity should be as low as possible
- thickness of material should be as thick as possible
what can geothermal energy do to heat energy
can turn heat energy from the earth into electrical energy
what is hydroelectric energy
water flowing is kinetic energy , we turn this into electrical for our home
how is energy transferred using mechanical work
a force moving an object through a distance
how is energy transferred through electrical work
charges moving due to a potential difference
how is energy transferred through heating
due to temperature difference caused electrically or by chemical reaction
how is energy transferred through radiation
energy transferred as a wave, eg lucnt and infrared lint radiation and infrared radiation are emitted from sun
examples of dissipation (2)
electrical cables warming up behind a tv as it is not uselfuk to have hot wires as berry is dissipated unto surrounding air
energy is usually lost by heating up surroundings thought sometimes energy is dissipated as sound waves
what is the internal store of energy
the sum of the kinetic energy stored in the particles of an object and the chemical energy stored in chemical bonds between particles in an object
how is more work done
- push with the same force for a longer distance
- push with a larger force for the same distance
what is the work done by a force equal to
the change in energy
what is lubrication
reduces frictional forces , can reduce the friction between the surfaces of objects that are rubbing together they are normally liquids
equation for power and work done
power (watts)= work done (j) divided by time (seconds, t)
how do we reduce unwanted energy transfer
- thermal insulation (reduces heat loss by having thicker material or with a lower thermal conductivity )
- lubrication (reduces the friction between surfaces of objects that are rubbing together )
disadvantage of geothermal energy
can only be used where there is volcanic activity close to the surface
advtange of geothermal energy
renewable
reliable
how to convert geothermal energy to electrical energy
magma heats rocks
hot rocks transfer heat to water in pipes
a turbine is rotated
the turbine rotated a generator
how can we think of storing energy
a bank account
you can earn money by doing work and then save it until there is something you won’t
you then transfer it to another person to buy whatever it is you want
