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NEWTONS LAWS OF MOTION NEWTON’S LAWS

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					NEWTON’S
 LAWS OF
 MOTION
Sir Isaac Newton             (1642 – 1727)

Newton was an English
physicist, considered one of
the most important scientists
of all time. Newton formulated
laws of universal gravitation
and motion—laws that explain
how objects move on Earth as
well as through the heavens.
He established the modern
study of optics—or the
behavior of light—and built
the first reflecting telescope.
               Forces
• A force is a push or a pull.
• In honor of Newton’s work with
  motion, the unit of force in the
  metric system is named for him.
• One newton is the amount of force it
  takes to accelerate a one kilogram
  mass at a rate of 1 meter/second 2.
• 1 n = 1kg-m/s2
Newton’s First Law (Part 1)
       (Law of Inertia)

An object at rest remains
 at rest unless acted on
 by an outside
 (unbalanced) force.
         Weight and Mass
• Weight is the            • Mass is the amount
  force with which           of matter
  gravity pulls an           contained in an
  object downward.           object.
• Units:                   • Units:
  – Metric – Newton (n)      – Metric – kilogram
  – English – pound (lb)       (kg)
                             – English - slug
• Varies depending
  on the object’s          • Remains constant
  location
 Newton’s First Law (Part 2)
• An object in motion remains in motion
  unless acted on by an outside
  (unbalanced) force.

• What does it take to keep an object
  in motion (ignoring friction)?
Both the car and its driver are traveling at 30 mph.
When the car stops suddenly, the driver continues
at 30 mph. Why?
     Newton’s Second Law
• If there is an unbalanced force,
  there will be an acceleration.
• The size of the acceleration depends
  on
  – the mass of the object
  – the size of the force
• This is usually written F = ma or
                             a = F/m
       Larger Forces Cause Larger
              Accelerations
                      Mass: 1545 kg
                      Horsepower: 395 hp
                      0 – 60 mph: 4.5 s


Mass: 1545 kg
Horsepower: 192 hp
0 – 60 mph: 8.4 s
        Larger Masses Cause Smaller
               Accelerations
                       Baseball mass = 0.14 kg (.32 lbs)
                       Distance = over 90 m (300 ft)




Shot put mass = 7.26 kg (16 lbs)
Distance = 23.12 m (75 ft)
      Newton’s Third Law
      (Law of Action – Reaction)

• For every action there is an equal and
  opposite reaction.

• If object A exerts a force on object
  B then object B exerts an equal force
  in the opposite direction on object A.

				
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posted:2/14/2012
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