# Newtonian Mechanics: Definition, Types, Assumptions [Gate Notes]

By BYJU'S Exam Prep

Updated on: September 25th, 2023

A branch of mechanics that deals with concepts of Newton’s law of motion as distance, time, and mass in a period of time are known as **Newtonian mechanics**. This Newtonian mechanics describes the motion of objects in routine life affected by the forces. Newtonian mechanics is a very straightforward formulation theory that deals with Newton’s second law of motion.

Generally, as for the theoretical approach, mechanics is split into three parts Newtonian, lagrangian and hamiltonian mechanics, but our routine work deals in Newtonian mechanics.

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**What is Newtonian Mechanics?**

The foundation of Newtonian mechanics is the application of Newton’s Laws of Motion, which make the assumption that space, time, and mass are absolute concepts and that motion occurs in an inertial frame. The Theory of Relativity goes against Newtonian concepts such as the absoluteness of time and the full separation of space and time.

**Assumption of Newtonian Mechanics**

As per Newtonian mechanics, some assumptions were made. In these assumptions, the system should be closed or isolated. It means the system’s total energy remains constant, and all the forces remaining in the system are unaccountable. This is the first assumption of Newtonian mechanics.

As per the second assumption of this theory, all particles in the system are slower than the light particles. it means that the light particles have the fastest speed in applied Newtonian mechanics.

**Types of Newtonian Mechanics**

Newtonian mechanics is also termed, classical mechanics. This theory is classified into two terms as Newtonian kinematics and Newtonian dynamics. In dynamics Newtonian mechanics, mathematical illustrations and results derive caused due to motion, while kinetic Newtonian mechanics provides results without any motion.

Newtonian mechanics is useful for the application of the law of motion, the study of astronomical bodies, relative motion and motions of objects on earth. It is the foundation of modern mechanics.

In Newtonian mechanics, the mass of the body does not change with the velocity, and the mass’s action also does not depend on the motion. As per the first law of motion, inertia force varies with motion, and all remains at rest. Some of the key objectives are-

- Newtonian mechanics involves constraint forces.
- Newtonian mechanics is used for vectors.
- This theory is applied to non-conservative forces as well.
- It does not require a systematic flow for deriving conservative laws.

**Applications of Newtonian Mechanics**

The applications of Newtonian mechanics are based on three laws of Newtonian mechanics principles. Each law has equal interpretation and is equally related to each other. These fundamental laws affect the physical properties of materials as well as their internal properties.

- The first law of Newtonian mechanics states that only external force application will cause the motion or stop of the object. By this application, we can observe in our routine life that every physical object needs an external force to change its initial state. For example, stopping balls, Moving cars, etc. This law is also called the inertia law of Newtonian mechanics.
- The second law of Newtonian mechanics states that the applied force depends on the product of mass and acceleration. It means higher acceleration gain to the low mass object or high applied force. In real life, when any object gets high speed, its weight reduces.
- The third law of Newtonian mechanics states that the action of a body will cause an equal and opposite reaction. This is mostly applied law in Newtonian mechanics as action-reaction law. Rocket propulsion uses this law to get sufficient thrust for lift-off.