P1 2.1 Energy transfers
Download
Report
Transcript P1 2.1 Energy transfers
The energy transferred in this
picture is…….
Learning objectives
• Describe the energy transfers in a range of
devices.
• Identify where energy is wasted.
• Explain why wasted energy is difficult to
use.
Forms of energy
click
Forms of energy
• Energy is needed to keep us working, and to operate
all the machines around us.
• Different forms of energy include…..
• Light, sound, electrical, potential and kinetic
energy.
• Energy can also be stored. Nuclear energy is stored
inside atoms. Food, fuels and electric batteries are
stores of Chemical energy.
• Anything that is squashed, stretched or twisted stores
Elastic potential energy.
• An object in a high position stores energy as
Gravitational potential energy.
Energy transfers
• Machines transfer energy between different
forms.
• An mp3 player transfers stored chemical
energy into electrical energy and sound
energy.
• Sometimes more than one transfer is involved.
The engine of a car transfers chemical energy
in the petrol into kinetic energy (useful) and
heat and sound (not useful and called wasted
energy).
• Click
(select no option)
Q) Label the useful and the wasted energy
Conservation of energy
• Energy cannot be created or destroyed, it
can only be transferred usefully, stored or
wasted (called dissipated).
• THE TOTAL AMOUNT OF ENERGY DOES
NOT CHANGE.
• This is called the principle of conservation
of energy.
Spreading out
• If you look at an energy transfer it can often
seem as if some of the energy has
‘disappeared’.
• For example, a car uses chemical
energy stored in its fuel.
• The fuel stores a lot of energy in a small space.
This chemical energy is eventually transferred
by heating into the surroundings, which become
warmer. This dissipated energy is very difficult to
use for further energy transfers.
Questions
What are the energy transfers of a torch?
You are running in sports day. What forms of
energy are you transferring that are A) useful
and B) wasted?
A car uses a litre of petrol when it is driven to
the shops and back. What happens to the
chemical energy that was stored in the petrol?
What are the forms of energy produced in a Bunsen
burner?
If energy cannot be destroyed, how can we ‘waste’
energy?
Draw a flow chart to show all the energy transfers
in a wind-up torch, starting with food. Show how
energy is wasted at each stage.