Today we will discuss the mechanics and its types:
The branch of physics which deals with the study of motion of material objects is called mechanics.
Mechanics can be classified into the following three main branches:
Statics: It is that branch of mechanics which deals with the study of objects at rest. In this branch, we study the motion of objects under the effect of forces in equilibrium. Time factor has no role to play in statics.
Kinematics: The branch of mechanics which deals with motion of material objects without taking into account the cause of motion (i.e. forces) is called kinematics. Time factor plays an essential role in kinematics.
Dynamics: the branch of mechanics which deals with motion of material objects by taking into account the cause of motion (i.e. forces) is called dynamics. As the cause of motion is force, therefore, dynamics is based on the concept of force.
Point object: An object whose dimensions (length, breadth, thickness etc.) are negligible as compared to the distance traveled by it is known as a point object. For example, a train moving over long distances, a shell fired from a gun, an aeroplane flying over long distances etc. may be considered as point objects.
Rest: A body is said to be at rest if it does not change its position with respect to its surroundings with the passage of time.
Motion: A body is said to be in motion if it changes its position with respect to its surroundings with the passage of time.
Rest and motion are relative terms:
A body may be at rest with respect to some objects but at the same time, it may be in motion with respect to some other objects. For example, the passengers sitting in a moving train are at rest with respect to another but they are in motion w.r.t. the objects lying outside the train and there is no body which at absolute rest.