Topic 3 - Conservation Of Energy Flashcards
efficiency
way of describing how good a machine is at transferring energy into useful forms
chemical energy
energy stored in food, fuel and batteries
kinetic energy
energy stored in moving objects
thermal energy
energy stored in hot objects
elastic potential energy
energy stored in stretched, squashed or twisted materials
gravitational potential energy
energy stored in objects in high position
atomic energy/nuclear energy
energy stored inside atoms
law of conservation of energy
energy cannot be created or destroyed; can only be transferred from one store to another
-> this means that the total energy transferred by system is the same as the energy put into the system
sankey diagram
the amount of energy that is transferred (it shows the useful and wasted energy)
-> the width of the arrows represents the amount of energy in joules
how is the efficiency of a machine described
between 0-1 - the higher the number the more efficient the machine
efficiency equation
efficiency = useful energy transferred by the device
total energy supplied to the device
what is wasteful energy
energy that is not used in the process and is transferred into the surroundings (e.g. when a lights turned on, heat gets dissipated into the surroundings; heat is wasted energy
electrical energy
energy stored in electricity
kinetic energy symbol equation
KE = 1/2 x m x v2
what does insulation do
slows down the rate at which energy is transferred out of a house by heating
conduction
vibrations are passed on between particles in a solid, easy energy transfer
—> metals are good thermal conductors and materials such as wood are poor thermal conductors (good thermal insulators)
convection
part of a fluid (liquid or gas) that is warmer than the rest rises and sets up a convection current
radiation
emission of energy in the form of waves through space or a vacuum
infrared radiation
a type of electromagnetic radiation
what effects the rate at which energy is transferred through material by heating
- it’s thickness
- thermal conductivity
- temperature difference across it
potential energy
type of energy stored in an object due to position relative to other objects
gravitational potential energy
the energy store in a object due to gravity (it’s position in a gravitational field)
gravitational potential energy equation
gravitational potential energy (J) = mass (kg) x height (m) x gravitational field strength (N/kg)
kinetic energy word equation
kinetic energy = 1/2 x mass x (speed)2
(J) (kg) (m/s)2
