Baseline (Aiming for 4):
Identify useful
and wasted energy during energy transfers and measure
friction.
Further (Aiming for 6):
Describe energy
dissipation and how this reduces the capacity of a system
to do work.
Challenge (Aiming for 8):
Apply the
concept of energy dissipation in a wide variety of
scenarios.
A television
Heating
transfer
Chemical
Store
(in coal)
Electric
current
transfer
Wave
transfer
(as light and
sound)
Thermal
store
(in the air)
An electric drill
Thermal
store
(in the air)
Chemical
Store
(in coal)
Electric
current
transfer
Force
transfer
Kinetic
Store
Wave
transfer
(sound)
An rising lift
Kinetic
Store
Chemical
Store
(in coal)
Electric
current
transfer
Force
transfer
Thermal
store
(in the air)
Gravitational
potential
store
Useful vs. Waste energy

Useful energy is energy in the place we
want it and in the form we need it.

Wasted energy is the energy that is not
useful and is transferred by an undesired
pathway.
Useful vs. Waste energy

Wasted energy is eventually transferred
to the surroundings, which become
warmer.

As energy dissipates (spreads out), it gets
less and less useful.
What’s wrong?
What is wrong with these statements about energy and
friction?

When a car stops at traffic lights, the speed energy is
destroyed by the brakes and is lost.

When fuel is burned in a car engine, energy is created
to make the car move.

When a car brakes, the thermal energy from the brakes
slows the car down.
Write corrected versions of each statement.