These laws, as the name suggests describe the relationship between forces acting on a body and its motion due to these forces. These were formed by Sir Isaac Newton and published on July 5, 1687. He would use these laws to explain more about the motion of many physical objects and systems. The Laws of motion form the basis of ‘Classical Mechanics'. Newton later showed that these laws, along with the Law of Universal Gravitation explained Kepler's laws of Planetary Motion.
Newton's first law states the "if the resultant force is zero, then the velocity of the body is constant". In simpler points:
- An object that is at rest will remain at rest until or unless an unbalanced force acts upon it.
- An object that is in motion will not change its velocity unless an unbalanced force acts upon it.
The Second Law states that "the net force on a particle is equal to the time rate of change of its Linear Momentum in an inertial frame (valid only for constant-mass systems)". From the Mathematical equation of the 2nd law, we see that net force applied to a body produces a proportional acceleration. The Third and Final law states that "to every action, there is always an equation and opposite reaction: or the forces of two bodies on each other are always equal and are directed in two opposite directions". The third law means that there is nothing such as a ‘unidirectional force', as forces are the interactions between different bodies.
These laws are applicable to macroscopic objects under everyday conditions. Newton's laws have been analyzed and verified for over 200 years, and it is clear that his laws were very precise, and were accurate approximations at the speeds of everyday life. Today when we talk of Modern Physics, all the new laws formulated are general validity, than Newton's Laws and apply to even non-classical physics. Newton's Laws will always be applicable in our daily lives, whether you know about them, or not!