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