Physics Flashcards
types of energy (26 cards)
magnetic
magnetic domains inside a
magnetic material that create a field;
thermal
a hot object stores more thermal
energy;
kinetic
(movement) – a substance may be made of vibrating particles;
chemical
energy is stored in the bonds
between atoms in a molecule;
ELECTROSTATIC
charged particles in an electric
field;
ELASTIC POTENTIAL (EPE)
in stretched springs, rubber bands, etc;
GRAVITATIONAL POTENTIAL (GPE)
the higher an object is, the more GPE it has;
NUCLEAR
stored within the nucleus of an atom.
MECHANICAL
this includes kinetic energy,
GPE and EPE;
ELECTRICAL
tiny charged particles
flowing around a circuit;
HEATING
transfer of thermal energy
from one place to another;
RADIATION
energy may be transferred in
waves of light or sound.
machines
A machine is a device that can convert one type of energy to another.
This can be represented by a simple energy flow diagram.
We can measure how much energy is transferred using a unit called the
joule (J).
conservation of energy
The CONSERVATION OF ENERGY states that:
energy cannot be created or destroyed; it can only
be converted from one form to another (or stored).
energy density
The energy density of a fuel is a measure of how much energy the fuel provides per unit
of its mass (how many joules provided per gram of fuel).
national grid
Electricity is generated in power stations (of different types), then it is transmitted around the country using a network of transformers and cables called the National Grid.
thermal power stations
A thermal power station heats water to create steam. This is often done by burning a fuel (storing chemical energy) or using nuclear energy.
burning fossil fuel
For many years, power stations have burned fossil
fuels (coal, oil and methane gas), but this leads to
problems. Firstly, the fossil fuels are non-renewable resources
– they take millions of years to form, but they are being used up at a much faster rate, so we will eventually run out.
the greenhouse effect
If the same amount of energy enters and leaves the Earth’s atmosphere, the Earth’s temperature remains
constant.
If more energy escapes, the planet cools down…
global warning
The problem is that the carbon dioxide we release stops some of the energy being released back into space – the Earth retains the energy, so the planet gets warmer – this is known as global warming.
whats is ‘work’
WORK is the process of TRANSFERRING
ENERGY. We say that an object has energy, but
the object does work when it transfers that
energy to another form.
work done = force x distance
what is ‘power’
POWER is the RATE at which WORK is done.
A more powerful object can do the same amount of work in less time, or more work at the same time, as a less powerful object.
power= work done / time taken
energy efficiency
For a machine to be considered as efficient, it must convert most of the input energy into useful forms, and waste little energy.
what is ‘efficiency’
EFFICIENCY is a measure of how much energy put into a device is
transferred to a useful form.
efficiency= useful energy output / total energy input
