Like Tamara, I’m guessing that you’re asking about what are called Newton’s three laws. Partly repeating her answer, these are:
1. An object won’t change its velocity unless something else acts on it.
2. The rate of change of the velocity, called the acceleration, a
, is given by a=F/m
, where F
is the force on the object and m
is the mass of the object.
3. The force exerted on object A by object B is exactly the same strength and exactly the opposite direction of the force exertd on B by A.
By themselves these laws don’t tell you much about the world, but once you start to include the rules for forces of interactions between objects, they describe a lot. For example Newton postulated that two bodies attract each other with a force proportional to the product of their two masses and inversely proportional to the square of the distance between them. The result: a complete description of planetary motion in the solar system.
Mike W. and Lee H.
(published on 07/11/07)