Definitions for energy topic Flashcards
closed system
a system that experiences no net change in its energy when energy transfers occur in it.
conservation of energy
the law that energy can be transferred, stored or dissipated but never created or destroyed.
efficiency
the ratio of useful energy output to total energy input.
elastic potential energy
the store of energy that stretched or compressed objects have. It is directly proportional to the stiffness constant and to the square of the extension or compression.
fossil fuels
coal, oil and gas.
gravitational potential energy
the store of energy that all raised matter has. It is directly proportional to the mass of the object, the distance that is risen and the gravitational field strength at that point.
joule
the unit used for energy. Equal to the work done when a force of one Newton acts over a distance of one metre.
kinetic energy
the store of energy that all moving matter has. It is directly proportional to the object’s mass and to the square of its velocity.
power
the rate at which energy is transferred, or at which work is done
renewable energy resources
an energy resource that can be replenished whilst it is being used.
specific heat capacity
the amount of energy required to raise the temperature of 1kg of a substance 1 degree.
spring constant
a measure of a spring’s stiffness. The greater the value, the greater the force required to stretch or compress the spring by a given distance.
system
a single, or group, of objects.
thermal conductivity
the higher this value is for a given material, the higher the material’s rate of energy transfer via conduction will be
waste energy
energy that isn’t usefully used for the purpose of the system.
