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Review Notes #10
Motion and Energy
Forces
• A force is either push
or pull.
• Can stop an object,
change its speed or
cause it to change
directions.
• Exs. Balanced(top
picture) and
Unbalanced (bottom
Picture) forces
Gravity
• All objects pull
on other objects.
• The amount of
pull depends on
mass and
distance.
• Large masses
close together
have a large
gravitational
force.
Motion
• Velocity is how fast an
object is moving and in
which direction.
• Also the change in
distance over a certain
time
• Acceleration is how fast
an object speeds up or
slows down.
• Slowing down is negative
acceleration.
• Change in Velocity over a
certain time.
Newton’s Laws
• 1st law – Law of
inertia. An object in
motion stays in
motion, object at rest
stays at rest unless
acted on by an
outside force.
• 2nd law – F = ma
• 3rd law – For every
action, there is an
equal and opposite
reaction.
Work and Machines
• Work – a force moves an
object a distance.
• A machine can do work.
• A machine puts in effort force
to overcome resistance
force.
• No machine is 100% efficient.
• Simple Machines – screw,
lever, pulley, inclined plane,
wheel and axle, wedge.
Energy
• Energy is the ability to do
work.
• Potential energy is stored. A
certain height.
• Kinetic energy is energy
because an object is moving.
• Energy can’t be created or
destroyed only change
forms.
• Mechanical, sound,
chemical, electrical, nuclear,
light, heat.
Waves
• Light and sound
travel in waves.
• Longitudinal waves
push and pull.
• Transverse waves go
up and down,
• High amplitude, large
volume
• High frequency, high
pitch.
Sound
• Produced by a
vibrating object.
• Doppler effect is
what you hear when
an object
approaches and
passes you.
• The denser the
medium the faster
sound travels.
• Temperature can
also influence speed
of sound.
Heat
• The vibrating motion of
molecules.
• Increase heat, molecules
speed up and spread out.
• Conduction – transfer by
touch
• Convections – transfer by
warm rising and cool
sinking
• Radiation – transfer by
waves through space.
Magnetism
• Magnets have
north and south
poles.
• Poles are where
the magnets are
strongest.
• Opposite poles
attract.
• Similar poles
repel
Electricity
• Like charges repel and opposites
attract.
• Conductors, let electricity pass
• Insulators prevent electricity from
flowing.
• Circuits – Need energy source,
path, and energy user.
• Series – one goes out they all go
out, add one user and the rest get
dimmer.
• Parallel – wired like your house.
Light
• Light travels in
straight paths called
rays.
• Light is 1,000,000
times faster than
sound.
• Light can be
absorbed, reflected,
or transmitted.
• Light can be bent or
refracted.
Electromagnetic Waves
• Light can travel through a vacuum in the
form of electromagnetic waves.
• Include x rays, radio waves, and other
things we see in every day life.