# Dynamics – Introduction

Dynamics is generally termed to be classical mechanics & it is a study which concerns the force or the torque apart from their effect on the motion. While on the other hand, kinematics is said to be the studies of the motion of objects but without the reference to its causes. To understand the principles of dynamics, scientists or the researchers in general have gone on to study as to how will a physical system develop or even charge over a period of time.

In addition to this, there is as study conducted about the causes of these changes on the system. Furthermore, it was Isaac Newton who had established fundamental physical laws. And these laws only govern the dynamics in physics. One will have to keep it in mind that though there are 3 laws of motion still the 2nd law of motion (found by Newton) is generally used. Whereas knowledge of the other 2 laws would certainly be an added advantage.

### What is linear dynamics?

Linear dynamics talks about the objects which move in one line besides the other terms such as force / mass / inertia / velocity (distance per unit time) / displacement (in units of distance) / momentum (mass times unit of velocity) / acceleration (distance per unit of the time squared).

### What is rotational dynamics?

On the other hand, there is rotational dynamics & this kind of dynamics is related to those objects which rotate or even move in a curved path. Hence, the quantities which come under this tag are moment of inertia or rotational inertia / torque / angular velocity (radians per unit time) / angular displacement (in radians or may be even in degrees) / angular momentum (moment of inertia times unit of angular velocity) & the angular acceleration (which is radians per unit of the time squared).

### What is force?

As per Newton, force is defined to be an exertion or a pressure which allows an object to accelerate. In simple terms, it can be stated to be the influence due to which a free body that is the object accelerates. Apart from this, it is possible to push or even pull as this allows the object to change direction besides having new velocity or even to deform either permanently or even temporarily. In other terms, force makes an object’s state of motion to change.

### Newton’s laws of motion

1. Newton’s 1st law of motion – if there is not any net force on a said object then the velocity of such an object remains constant. Moreover, this object can either be at rest or keep moving in a direction with constant speed.
2. Newton’s 2nd law of motion states that the rate of change of the linear momentum P of the object equals to the net force.
3. On the other hand, Newton’s 3rd law states that when a body exerts force on another body then the 2nd body simultaneously exerts force on the 1st Thus, it means that both the bodies are equal in magnitude besides being opposite in direction.