conservation and dissipation of energy Flashcards
(21 cards)
what is a system?
an object or a group of objects
what is a closed system?
where no energy can escape to or enter from the surroundings. the total energy in a closed system never changes
kinetic energy store
energy an object has because it is moving
gravitational potential energy store
energy an objects has because of its height above ground
elastic potential energy store
energy an elastic object has when it is stretched or compressed
thermal energy store
energy an object has because of its temperature
chemical energy store
energy that can be transferred by chemical reactions involving foods, fuels, and the chemicals in batteries
nuclear energy store
energy stored in the nucleus of an atom
magnetic energy store
energy a magnetic object has when it is near a magnet or in a magnetic field
electrostatic energy store
energy a charged object has when near another charged object
how can energy can be transferred to and from different stores?
heating, waves, electricity and forces
heating
energy is transferred from one object to another object with a lower temperature
waves
waves (e.g. light and sound) can transfer energy
electricity
an electric current transfers energy
forces (mechanical work)
energy is transferred when a force moves or changes the shape of an object
work done
the energy transferred when a force moves an object over a distance
what is power?
how much work is done per second and is measured in watts
law of conservation of energy
energy CANNOT BE DESTROYED it can only be transferred usefully, stored, or dissipated (wasted)
lubrication
lubrication is a way of reducing unwanted energy transfer due to friction
streamlining
a way of reducing energy wasted due to air resistance or drag in water
what is efficiency?
a measure of how much energy is transferred usefully
