Forces and Newton

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• Forces and Newton

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1. Forces

• A force is a push or a pull.
• Force is measured in Newtons.

pull
push
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• Exerting a force on an object causes its motion
  to change.
• So, a force causes an object to accelerate.

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For Example

• When you throw a ball, your hand exerts a force
  on the ball, causing it to speed up.
• The ball has an acceleration because the speed of
  the ball has increased.

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2. Balanced and Unbalanced Forces
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• Two or more forces are balanced forces if their
  effects cancel each other out.

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• If the effects of the forces dont cancel each
  other, the forces are unbalanced forces.

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3. Combining Forces

• When more than one force acts on an object, the
  forces combine.
• The combination of all forces is the NET FORCE.

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• If the forces are in the same direction, they add
  together to form the Net Force.

net force
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• If two forces are in opposite directions, the net
  force is the difference between the two forces .

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• For balanced but opposite forces, the net force
  is zero.

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Individual practice Calculating Net Force
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4. Newton's Laws of Motion

• There are 3 Laws of Motion discovered by Sir
  Isaac Newton.
• Newtons First Law
• Newtons Second Law
• Newtons Third Law

1643 - 1727
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5. Newton's First Law

• An object at rest will remain at rest or an
  object moving straight at constant speed will
  continue this motion until a force acts on it.

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For Example

• A book on a table will remain at rest until a
  force acts on it.
• A thrown football wont change its motion, that
  is, speed up or slow down, unless a force acts on
  it.

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6. Newton's Second Law

• An object that has a force acting on it will
  accelerate in the direction of the force.

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Which one will hit the ground with the greatest
force?
F m x a
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7. Newton's Third Law

• Forces always occur in equal but opposite pairs.

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• Newtons Third Law

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For every action, there is an equal and opposite
reaction.
Newtons Third Law of Motion
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Another example of Action -Reaction Forces
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YEA!
We are finished!