Force ( F )                                            Centrifugal Force (Chistiaan Hygens in
                                                       1659)
  A force is a push or pull upon an object
   resulting from the object"s interaction with        It is the tendency of an object following a
   another object.                                     curved path to fly outwards, away from the
  It is a product of mass and acceleration.           center of the curve. It is the inertia of motion.
  Its unit is newton and represented by the           e.g. Mud flying off a tire; children pushed out
   symbol F.                                           on a roundabout.
  Force = mass x acceleration
  or F  ma                                           Centripetal Force (Isaac Newton in 1684)
  1N = 1 kg x 1m/s2.
                                                       The force that keeps an object moving with a
                                                       uniform speed along a circular path. e.g.
                                                       Satellite orbiting a planet.
                        NEWTON’S LAWS OF MOTION
              Isaac Newton (1643-1727), the physicist who formulated the laws of motion
Newton"s First Law of Motion
  It states that every object will remain at          Newton"s Second Law of Motion
   rest or in uniform motion in a straight line
   unless compelled to change its state by the             It explains how the velocity of an object
   action of an external force.                             changes when it is subjected to an external
  This is normally taken as the definition of              force.
   inertia. (Galileo"s concept "Law of                     It defines a force to be equal to change in
   Inertia")                                                momentum (mass times velocity) per
  The key point here is that if there is no net            change in time.
   force acting on an object (if all the                   Newton also developed the calculus of
   external forces cancel each other out) then              mathematics, and the "changes" expressed
   the object will maintain a constant                      in the second law are most accurately
   velocity. If that velocity is zero, then the             defined in differential forms. For an object
   object remains at rest. If an external force             with a constant mass m, the second law
   is applied, the velocity will change                     states that the force (F) is the product of
   because of the force.                                    an object"s mass (m) and its acceleration
  The first law can be stated mathematically               (a):
   as                                                      Fm
                                                                  dv
                                                                      ma
               dv                                                 dt
   F  0  dt  0
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