changes in energy

what is the conservation of energy

energy can be transferred usefully, stored or dissipated but it cannot be created or destroyed

what does dissipated mean

the spreading out and transfer of energy stores into less useful forms such as thermal energy causing the surroundings to heat up. dissipated energy is often referred to as ‘wasted’ energy as it is not transferred to a useful output

what happens when a sky diver jumps out of a plane

begins to loose energy from the gravitational potential energy store as his heigh decreases and his kinetic energy store increases as his speed increases

what happens with the energy in the battery of phones

all phones contain a battery that contains chemical energy. when the phone is in use the chemical energy store of the battery decreases. the energy is transferred through the electrical work pathway to light up the screen and produce sound. thermal energy is also produced as the chemical energy is also transferred to the internal energy store and light and sound

what are the eight stores of energy

magnetic

internal (thermal)

chemical

kinetic

electrostatic

elastic potential

gravitational potential

nuclear

what is a magnetic energy store and examples

it is when the repelling poles have been pushed together or when attracting poles have been pulled further apart

examples:

fridge magnets, compasses, maglev trains

what is a internal energy store and examples

the total kinetic and potential energy of the particles in an object, in most cases this is the vibrations - also known as the kinetic energy - of particles. in hotter objects, the particles have more internal energy and vibrate faster

examples:

human bodies

hot coffees

stoves

hobs

ice particles vibrate slower but still have energy

what is a chemical energy store and examples

the energy stored in the chemical bonds such as those of a moving object

e.g.

foods

muscles

electrical cells

what is a kinetic energy store and examples

the energy of a moving object

e.g.

runners

buses

comets

what is a electrostatic energy store and examples

the energy stored when repelling charges have been moved closer together or when attracting charges have been pulled further apart

e.g.

thunderclouds

ran de graaff generators

what is a elastic potential energy store and examples

the energy stored when an object is stretched or squashed

e.g.

drawn catapults

compressed springs

inflated balloons

what is a gravitational potential energy store and examples

the energy of an object at height

e.g.

aeroplanes

kites

mugs on a table

what is a nuclear energy store and examples

the energy stored in the nucleus of an atom

e.g.

uranium nuclear power

nuclear reactors

what is a pathway

energy can be transferred from one store into another as one store empties another store fills

wat are the four pathways for transferring energy

mechanical work

electrical work

heating

radiation

what is the mechanical work pathway

a force moving an object through a distance

what is the electrical work pathway

charges moving due to a potential difference

what is the heating work pathway

due to a temperature difference caused electrically or by chemical reaction

explain the energy in a swing

when its at the top it has no kinetic energy and it is at the gravitational potential energy. when its at the lowest point it has maximum kinetic energy and minimum gravitational potential energy. when it carries on going up at it reaches the highest gravitational potential energy

explain the energy in a boat accelerating by the force of the engine

the boat pushes through the water and it loses chemical energy as fuel is burned and then it gains kinetic energy as it gains speed

explain the energy when a water is bought to boil in an electric kettle

the electricity going through the kettle increases the thermal energy and that increases the thermal/internal energy of the water which increases the temperature of the water

explain the energy of a car breaking in an emergency

the kinetic energy is transferred to thermal energy of the surroundings by the work from by the force of friction on the breaks

explain the energy in a snowball hitting a wall

the kinetic energy is transferred into thermal energy of the surroundings by the work done by the force from the wall

explain the energy of a child at the top of a swing

gravitational potential energy transfers to kinetic energy as the child increases in speed and to internal energy as a result of the friction

what is a sankey diagram

Sankey diagrams start off as one arrow that splits into two or more points. This shows how all the energy in a system is transferred into different stores.

Sankey diagrams are really useful when the amount of energy in each of the energy sources is known. The width of the arrow is drawn to scale to show the amount of energy.

the first arrow shows what the input energy and the arrow that goes straight shows the useful output and the arrows that comes out and goes down shows the wasted energy