Transcript MOVEMENT AND CHANGE

MOVEMENT AND CHANGE
Forms of energy
Gravitational potential
energy
FORMS OF ENERGY

There are several forms
of energy.
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Thermal energy
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Caused by the
movement energy of
molecules.
FORMS OF ENERGY

Kinetic energy (KE)
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This is the energy all
moving objects have.

A moving lorry has lots
of kinetic energy!
FORMS OF ENERGY
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Chemical energy
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Energy which is stored
in food or fuels
FORMS OF ENERGY

Sound and light
energy
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Common types of
energy
FORMS OF ENERGY
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Electrical energy
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Very common and
useful

(Magnetic energy is
always connected with
electrical energy)
FORMS OF ENERGY
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Nuclear energy
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Energy stored in the
centre of the atom
FORMS OF ENERGY

Gravitational potential
energy

When an object is
moved to a higher
place it gains stored
energy which it can
give out if it falls
down.
The Principle of Conservation of
Energy

Energy can be changed from one form to
another but it cannot be created or
destroyed.
Falling under gravity
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A diver may use 6000J of
energy climbing to the top of
a board.
At the top of the board he
has 6000 J of gravitational
potential energy (PE) but no
kinetic energy (KE).
As he dives, his PE is
converted into an equal
amount of KE
Falling under gravity

The total amount of PE
+ KE is always 6000J!
The Pendulum
The Pendulum

When a pendulum
swings to and fro, its
energy is constantly
changing from potential
energy (PE) to kinetic
energy (KE) and back
again.
The Pendulum
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The energy eventually
is converted to heat by
friction with the air.
This heat is “low grade”
energy and we can not
make use of it
All energy eventually
becomes low grade.
Calculating Potential Energy

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For a weight lifter lifting
a mass of 200 kg up a
height of 2 m we can
work out the gain in
potential energy.
Potential energy = work
done = weight x height
lifted
Calculating Potential Energy

On Earth
weight (in N) =
mass (in kg) X 10 so:
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PE = mass x 10 x height
Calculating Potential Energy
Gravitational PE = mass x g x height
(in joules)
(kg) (N/kg) (m)

On Earth g = 10, but g has different values
on other planets