# Introduction of Applied Mechanics

## Mechanics

Mechanics is the branch of science which deals with the study of the action of forces on bodies.

definition, Mechanics deals with the presence of forces and its effects on different bodies.

The Principles of mechanics are even applied by laymen to facilitate the easy working of life. As for example, labours use an iron rod to move heavy wooden logs without knowing the principle of the lever.

Similarly in our everyday life, we see the application of laws of mechanics like the use of balance, the stress in bridges and trusses, the balancing act of a person on a rope, the motion of vehicles, etc.

### Applied Mechanics

Applied mechanics is the branch of engineering which deals with the study of the use of different laws and the principles of mechanics for the solution of various engineering problems is called Applied Mechanics.

We can also say, Applied Mechanics is an arm of the physical science and also the practical uses of mechanics.

### Importance of Applied Mechanics

For an engineer, the study of applied mechanics is very important because the knowledge of this subject enables him to properly design all types of structures and machines.

Therefore, it is very essential to study the various law of applied mechanics to determine the various forces acting in a frame structure, flight of an aeroplane and projectiles etc., so as to accomplish the design and construction in the engineering field.

Applied Mechanics inspect the reaction of bodies (Solid and fluid) or system of bodies to external forces. It bridges the gap between physical theory and its application to technology.

### Branches of Applied Mechanics

Applied Mechanics has mainly two branches namely statics and dynamics:

(a) Statics: The branch of applied mechanics which deals with the action of forces on bodies at rest is called statics.

All such bodies which are acted upon by the external forces but are either at rest or in uniform motion come under the scope of statics.

Example: The study of different types of forces acting on a book lying on a table.

(b) Dynamics: It is the branch of applied mechanics which deals with the action of forces on bodies in motion.

Example: Functioning of a watch and the study of different forces acting on its different parts.

Dynamics is further sub-divided into two parts,

i) Kinetics

ii) Kinematics

(i) Kinetics: It is the branch of dynamics which deals with the study of forces responsible for the motion of a body.

Example: Study of forces  for acceleration and retardation of a moving body comes under the scope of kinetics.

(ii) Kinematics: It is the branch of dynamics which deals with the study of the motion of bodies without any reference to the forces causing the motion.

Example: Freely falling bodies under gravity, relative velocities of boat and river.

### Rigid Body

A rigid body may be defined as a body which does not change its shape and size under the action of forces.

Actually, nobody in this universe is perfectly rigid. While few changes going on in a body under the action of external forces depending upon its shape and size. But these changes are very small as compared to the size of the body and so the body is considered as a rigid body.

### Mass

Mass is the amount of matter carried in the body. Unit of mass in M.K.S and S.I. the system is kg.

Note: Your mass does not change when you go to the moon, but your weight does. Mass represents the amount and weight shows the size of gravity.

### Weight

Weight of any body is a force through which the body is attracted to the centre of the earth.

Weight = Mass of a body * Acceleration to the gravity

W = m * g

The value of g is usually taken as 9.81 m/s­­­­2 in M.K.S and S.I. system.

The unit of weight in M.K.S. is kg wt and in S.I. is Newton (N).