PHY101- LEC 4
Newton’s Third Law of Motion states that for every action force there is a reaction
force that has the same magnitude but points in the opposite direction.
Newton’s Theory of Gravitation
Newton’s Laws of Motion can be used to predict the paths of object in the night shy
such as the Moon, the planets, and the stars.
Newton developed a simple expression for the gravitational force between two
objects of mass M and mass m that are separated by a distance R.
FG = GMm/R2
G is called the Gravitational Constant
This expression does not depend on the composition of the object
The unit of force is called a Newton, in honour of Sir Isaac Newton. You can refer its
units for F=ma. If mass m is in kilograms kg and acceleration a is in m/s2
Then a Newton is a kg m/s2
All objects exert attractive gravitational force on one another