Newton's Laws of Motion

Sir Isaac Newton published Philosophiae Naturalis Principia Mathematica in 1687. This text contains the three basic laws on which mechanics is based

Newton's First Law
Every body continues in its state of rest or of uniform motion in a straight line unless acted on by some external force.

No force = no acceleration
Newton's Second Law
The rate of change of momentum of a body is directly proportional to the external force acting on the body and takes place in the direction of the force.

F = force acting on the body [N]
m = mass of the body [kg]
v = velocity of the body [ms-1]

the rate of change of velocity is the acceleration
a = acceleration of the body [ms-2]
Newton's Third Law
If a body A exerts a force on body B, then B exerts an equal and oppositely directed force on A.

Weight is the magnitude of the force of gravity.

See also: Equations of Motion, Inertial Reference System, Keplers Laws, Newton, Isaac, Newtonian Mechanics, Noninertial Reference System, Special Theory of Relativity.

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Subjects: Physics

Newtons Castle A stimulating journey into the revelations of Sir Isaac Newton. Learn about his discovery of Gravity and Optical Theories.