Energy dissipation/energy and efficiency- Electrical appliances/energ
● Useful energy is energy in the place we want it and in the form we ● The electrical applianc
need it, wasted energy is energy that is not useful and transferred should waste energy a
by an undesired pathway ● Light bulb - useful lig
● Whenever energy is transferred, some is transferred usefully, the rest from filament heating
is dissipated and stored in less useful ways ● Electrical heater - use
● Energy becomes more useful the more it spreads out from the glowing filam
● The more powerful an
● No energy transfer can’t be more than 100% efficient because you
can never get more energy from a machine than you put into it
● Efficiency can be increased by reducing the energy they waste, for
example lubricating the moving parts to reduce friction, using wires
with as little electrical resistance, streamlining the shapes of moving
objects to reduce air resistance
P1 : Conservatio
Gravitational potential energy stores/kinetic energy and elastic stores-
● The GPE store of an object increases when it moves up and decreases
when it moves down
● Useful energy is energy in the place we want it and in the form we ● The electrical applianc
need it, wasted energy is energy that is not useful and transferred should waste energy a
by an undesired pathway ● Light bulb - useful lig
● Whenever energy is transferred, some is transferred usefully, the rest from filament heating
is dissipated and stored in less useful ways ● Electrical heater - use
● Energy becomes more useful the more it spreads out from the glowing filam
● The more powerful an
● No energy transfer can’t be more than 100% efficient because you
can never get more energy from a machine than you put into it
● Efficiency can be increased by reducing the energy they waste, for
example lubricating the moving parts to reduce friction, using wires
with as little electrical resistance, streamlining the shapes of moving
objects to reduce air resistance
P1 : Conservatio
Gravitational potential energy stores/kinetic energy and elastic stores-
● The GPE store of an object increases when it moves up and decreases
when it moves down
