Newtons First Law of Motion

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Newtons First Law of Motion
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Sir Isaac Newton

• 1643-1727
• His accomplishments in mathematics, optics, and
  physics laid the foundations for modern science
  and revolutionized the world.
• His works are published in "Opticks" and
  "Principia
• invented integral calculus
• defined the laws of motion and universal
  gravitation
• constructed the first reflecting telescope

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Newtons First Law of Motion

• An object at rest tends to stay at rest and an
  object in motion tends to stay in motion with the
  same speed and in the same direction unless acted
  upon by an unbalanced force.

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What is a balanced force?

• Since these two forces are of equal magnitude and
  in opposite directions, they balance each other.
• The book is said to be at equilibrium. There is
  no unbalanced force acting upon the book and thus
  the book maintains its state of motion.
• When all the forces acting upon an object balance
  each other, the object will be at equilibrium it
  will not accelerated.

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What is an unbalanced force?

• The book is in motion and at the moment there is
  no one pushing it to the right.
• There is no force present to balance the force of
  friction.
• As the book moves to the right, friction acts to
  the left to slow the book down.
• There is an unbalanced force and as such, the
  book changes its state of motion.
• The book is not at equilibrium and subsequently
  accelerates. Unbalanced forces cause
  accelerations.

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• Balanced or Unbalanced?

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• An object at rest tends to stay at rest and an
  object in motion tends to stay in motion with the
  same speed and in the same direction unless acted
  upon by an unbalanced force.

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Examples of Newtons 1st Law

• blood rushes from your head to your feet while
  quickly stopping when riding on a descending
  elevator.
• the head of a hammer can be tightened onto the
  wooden handle by banging the bottom of the handle
  against a hard surface.
• a brick is painlessly broken over the hand of a
  physics teacher by slamming it with a hammer.
  (CAUTION do not attempt this at home!)
• to dislodge ketchup from the bottom of a
  ketchup bottle, it is often turned upside down
  and, thrusted downward at high speeds and then
  abruptly halted.
• headrests are placed in cars to prevent
  whiplash injuries during rear-end collisions.
• while riding a skateboard (or wagon or
  bicycle), you fly forward off the board when
  hitting a curb or rock or other object which
  abruptly halts the motion of the skateboard.

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More examples- Law of Inertia

• Truck and ladder
• Car and the wall