Zusammenfassung der Ressource
Using energy
- Different forms of energy
- Chemical energy = energy stored in fuel
(including food), and is released when
chemical reactions take place
- Kinetic
energy is the
energy of a
moving object
- Gravitational
potential energy (or
GPE) is the energy
of an object due to its
position
- Electrical energy is
energy transferred by
an electric current
- Thermal (heat) energy is
the energy of an object
due to its temperature,
partly because of the
random kinetic energy of
the particles of the object
- Elastic (or strain)
energy is the
energy stored in a
springy object
when we squash
or stretch it
- Sound energy is
energy created
from sounds
- Energy can only be
transformed from one
form to another
- Energy cannot be lost it can
ONLY be changed from 1
form to another
- EXAMPLE= torch chemical energy in battery =>
electrical energy => light energy + thermal energy
- Energy conservation
- CONSERVATION OF ENERGY ! --
energy cannot be created or destroyed
- Useful energy, Wasted energy ,Efficiency
- Useful energy is energy
transferred to where we want it
to go
- Wasted energy is
energy which is not
usefully transferred
- Wasted energy
spreads out to its
surroundings.
- EXAMPLE = the gears of a
car get hot when the car is
running, so thermal energy
transfers from the gear box to
the surrounding air
- Useful energy
eventually transfers
to its surroundings
too
- EXAMPLE= , the useful
energy supplied to the
road wheels of a car
changes into thermal
energy of the tyres, the
road and the surrounding
air
- Energy becomes less useful when its spread out
- The Sankey diagram to the left shows how we can
represent useful and wasted energy outputs from a
machine or appliance
- We can sum this up by using this general
equation: energy supplied = useful energy
delivered + energy wasted
- For any device that
transfers energy, we can
use this to work out the
energy efficiency of it:
- useful energy transferred by
__________________________________
device total energy supplied to device
- Efficiency =