p1 - energy Flashcards
8 energy stores
thermal
kinetic
gravitational potential
elastic potential
chemical
magnetic
electrostatic
nuclear
how is energy transferred
mechanically - a force doing work
electrically - moving charges
heating
radiation
what happens when a system changes
energy is transferred, it can be transferred into or away from the system between different objects in the system or between different types of energy stores
what are closed systems
systems where neither matter nor energy can enter or leave. the net change is always 0
when can work be done
when current flows or by a force moving an object
what does movement mean
energy in an object’s kinetic energy store
how is energy transferred to the kinetic energy store
when an object speeds up and is transferred away from this tore when an object slows down
the energy in the kinetic energy store depends on what
the object’s mass and speed
the greater its mass and the faster its going, the more energy there will be in its store.
kinetic energy formula
E = 0.5 x m x v squared
where do raised objects store energy
in gravitational potential energy store
the amount of energy in a g.p.e store depends on what
the object’s mass, height and the strength of the gravitational field the object is in
gravitational potential energy store equation
E = mgh
how do falling objects transfer energy
energy from its gravitational potential energy store is transferred to its kinetic energy store
what happens for a falling object when there is no air resistance
energy lost from the g.p.e store = energy gained in the kinetic energy store
what does air resistance cause energy to do
it causes some energy to be transferred to other energy stores such as thermal energy stores of the object and surroundings
where does stretching transfer energy to
elastic potential energy store
elastic potential energy store equation
E = 0.5 x k x e squared
what is a system
an object or group of objects
what is the specific heat capacity of a substance
the amount of energy required to raise the temperature of one kilogram of the substance by one degree Celsius
what is power defined as
the rate at which energy is transferred or the rate at which work is done
equation for power
energy transferred / time
can energy be created or destroyed
no
the higher the thermal conductivity of a material =
the higher the rate of energy transfer by conduction across the material
the energy efficiency for any energy transfer can be calculated
using the equation:
useful output energy transfer / total input energy transfer
the main energy resources available for use on Earth include:
fossil fuels (coal, oil and gas), nuclear fuel, bio-fuel, wind, hydroelectricity, geothermal, tides, Sun and water waves
what is a renewable energy source
can be replenished as it is being used
uses of energy resources
transport, electricity generation and heating
