NEWTON’S LAWS OF MOTION


1ST LAW - A body remains in a constant state of motion unless acted upon by a net force. (Law of Inertia)

2ND LAW - When a body is acted upon by a net force, that force produces an acceleration which is directly proportional to the impelling force and inversely proportional to the body’s mass, i.e.,

Fnet = ma.

3RD LAW - If body A exerts a force on body B, then body B exerts a numerically equal, but oppositely directed force on body A. (Law of Action-Reaction)
  • Note:  For a moving body, both the net force and the acceleration can be broken down into two
               mutually perpendicular components, a tangential component which is parallel to the motion
               and a centripetal component which is perpendicular to the motion, i.e.,     Fnet = Ft + Fc and
               a = at + ac.  Newton's 2nd Law applies individually to the components as well as to the total
               force and acceleration, i.e., Fnet = ma , but also Ft = mat and Fc = mac    .

     

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