p1
whats a system
an object or group of objects
what happens when a system changes
energy is transferred to the surroundings or between its stores
whats a closed system
where no energy can escape or enter to or from the surroundings
what are the energy stores
kinetic
gravitational potential
electrostatic
magnetic
elastic
thermal
nuclear
chemical
whats kinetic energy
energy an object has bc its moving
whats gravitational potential energy
energy an object has bc of its height above the ground
whats elastic potential energy
energy an object has when its stretched or compressed
whats thermal energy
energy an object has bc of its temperature (total kinetic and potential energy of the particles in an object)
whats chemical energy
energy that can be transferred by chemical reactions
whats nuclear energy
energy stored in the nucleus of an atom
whats magnetic energy
energy a magnetic object has when its near a magnet of magnetic field
whats electrostatic energy
energy a charged object has when uts near another charged object
how is energy transferred
heating
waves
electricity
forces
how is energy transferred through heating
energy is transferred from one object to another object with a lower temperature
how is energy transfered through waves
by radiation
how is energy transfered through force
energys transfered when a force moves or changes the shape of an object
how is energy transfered through electricity
when an electric current flows
what are the factors that affect the rate of heat loss
the thickness of the walls and roof
the thermal conductivity of the walls and roof
how can thermal conductivity be reduced
by using thermal insulators
whats a thermal insulator
a material that has a low thermal conductivity as the energy transfer is low
what does the energy transfer per second depend on
materials thermal conductivity
the temperature differency between two sides of a material
the thickness of thhe material
gravitational potential energy equation
mass x gravitational field strength x height
kinetic energy equation
0.5 x mass x speed^2
whats power
work done / energy transferred
power equation
work done / time
elastic potential energy equation
0.5 x spring constant x extention^2
can energy be created
energy cant be created or destroyed only transferred stored or dissipated (wasted)
where does all energy end up going
it ends up being transfered to the thermal energy store of the surroundings
whats lubrication
a way of reducing unwanted energy transfer due to friction
whats streamlining
a way of reducing energy wasted due to air resistance or drag in water
whats efficiency
a measure of how much energy is transfered usefully
efficiency equation
useful power output / total power input