Newton's [ the first ]

• Newton's First Law of Motion

  An object at rest remains at rest, and an object in motion remains in motion at constant speed and in a straight line unless acted on by an unbalanced force
• Newton's Second Law of Motion

  The acceleration of an object depends on the mass of the object and the amount of force applied
• Newton's Third Law of Motion


  Whenever one object exerts a force on another object, the second object exerts an equal and opposite on the first
• Sir Isaac Newton worked in many areas of mathematics and physics
• Newton developed the theories of gravitation when he was only 23 years old


  1666
• Newton presented his three laws of motion in the "Principia Mathematica Philosophiae Naturalis"


  1686
• By developing his three laws of motion, Newton revolutionized science
• Newton's laws together with Kepler's Laws explained why planets move in elliptical orbits rather than in circles
• There is a short movie featuring Orville and Wilbur Wright and a discussion about how Newton's Laws of Motion applied to the flight of their aircraft
• Newton's Second Law


  Force
• Newton's Second Law


  • The acceleration of an object depends on the mass of the object and the amount of force applied
  • Force is equal to change in momentum (mass times velocity) per change in time
  • Momentum is defined as the mass m of an object times its velocity V
• Newton's Second Law


  1. Force = (m₁ * V₁ - mo * Vo) / (t₁ - to)

  2. If mass is constant: F = m * (V₁ - Vo) / (t₁ - to)

  3. F = m * a
• Velocity, acceleration, momentum and force are vector quantities
• An external force F is applied to an airplane

  The airplane's mass and velocity change from mo, Vo to m₁, V₁
• The weight of the fuel is probably small relative to the weight of the rest of the airplane, especially if we only look at small changes in time
• If discussing the flight of a baseball, the mass remains constant
• If discussing the flight of a bottle rocket, the mass does not remain constant and we can only look at changes in momentum
• The change in velocity divided by the change in time is the definition of the acceleration a
• The second law reduces to F = m * a for objects with constant mass
• An object subjected to an external force will accelerate