Transcript Fraction Too Much Friction

Tuesday, 12 April 2016
Forces
A force is a push, pull
or twist upon an object
resulting from the
object's interaction
with another object.
Examples of Forces
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Electrical
Magnetic
Gravity
Weight
Friction
Nuclear
Buoyancy or lift
Force
Copy
Forces act on objects and cause changes
in:
 Motion
 Speed
 Direction
 Shape
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 Force
has symbol F
 Measured in Newton (N)
Measuring Forces
Mass
Force
The most useful thing you will ever know:
Mass (kg)
F=ma
Force (N)
Acceleration
(ms-2)
Some History…
Isaac Newton
What did he do?
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Mathematician, physicist, astronomer,
alchemist, chemist, inventor and natural
philosopher
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Created the basics of classical mechanics
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Almost all of the physics you will do is
based on Newton’s Laws.
Laws
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1st Law: Law of Inertia
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2nd Law: F=ma
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3rd Law: Every action has an equal and
opposite reaction
Telescope
The Principia
Isaac Newton
I do not know what I may appear to the world, but
to myself I seem to have been only like a boy
playing on the sea-shore, and diverting myself in
now and then finding a smoother pebble or or a
prettier shell than ordinary, whilst the great
ocean of truth lay undiscovered before me.
Isaac Newton
Isaac Newton
Nature and natures laws lay hid in night;
God said ‘let Newton be’ and all was light.
Alexander Pope
Forces
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Contact Forces: Must touch the object on
which it acts.
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Non-Contact Forces: Force that is distant
but is still pushing or pulling.
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Force (F) is measured in newtons
Balanced Forces
Balanced Forces
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Forces are balanced when they are the
same in a particular direction.
Eg the horizontal forces are the same and
the vertical forces are the same.
Unbalanced Forces
Net Force
12 N
2N
10 N
What does this mean?
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An object will move in the direction that
the net force ‘pushes’ it.
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If the net force on a car is 10N forwards
what will be happening? It is changing in
speed or direction.
The Four Forces
Reaction force
Friction
Push force
Weight force
Practice problems