physics topic 1 - energy Flashcards
(22 cards)
conservation of energy
the law that energy can be transferred, stored or dissipated but never created or destroyed
what is a reneqable energy resource
an energy source which can be replenished whilst it is being used
what is specific heat capacity
The amount of energy needed to raise the temperature of 1kg of a substance by 1 degrees celcius.
what is Work done
the energy transferred when a force acts over a distance
what is the definition of power (Watts)
The rate at which energy is transferred, or at which work is done
what is a closed system
a system that experiences no net change in its total energy when energy transfers occur within it.
what is efficiency
the ratio of useful output energy transfer to total energy input
what is waste energy
energy that isnt usefully used for the purpose of the system
what is thermal conductivity
the higher this value is for a given material, the higher the materials rate of energy transfer via conduction will be
what are the fossil fuels
oil, coal, gas
define dissipation
energy being transferred to its surroundings
what environmental impact does coal have
produces CO2 and sulfuric acid which contributes to acid rain which destroys plants and buildings
what environmental impact does oil cause
produces CO2, nitrogen dioxide and sulphur acid. if there is a spill it would cause environmental issues
what environmental impact does gas have
produces CO2
what environmental impact does nuclear energy resources have
produces radioactive waste
when energy is transferred in a closed system what happens
total energy does not change
how can the efficiency of an energy transfer be increased
by increasing the useful output by reducing the wasted energy
2 methods to reduce energy waste
lubrication - motor oil to reduce friction
thermal insulation - double glazing
what is thermal conductivity
the higher the thermal conductivity of a material, heat is allowed to transfer by conduction across a material.
name 3 chemical energy stores
food
fuel
batteries
describe the energy changes in a filament light bulb
- electrical energy is transferred into light and heat energy
- light is the useful energy form, heat is the waste energy
