Introduction and Basic Concepts of Mechanics

Mechanics:

Mechanics is the branch of science which deals with the motion, forces and their effect on bodies.

Engineering mechanics:

Engineering Mechanics is a branch of applied science concerned with the bodies which are at rest or in motion under the action of forces .

Applications of Engineering Mechanics:

The following are the applications of engineering mechanics:

1. Design of Buildings

2. Design of Bridges

3. Engines

4. Design of Machinery

5. Missiles and Aeroplanes

6. Trusses and Frames(Steel Structures)

Statics : The branch of mechanics concerned with bodies at rest and forces in equilibrium.

Where W = Weight of body and N = Normal reaction .

Dynamics : The branch of mechanics which deals with the study of bodies which are in motion.

Where w = weight P = applied force N = Normal reaction

Kinematics: The study of motion of bodies without considering the forces acting on them.

Kinetics: The study of motion of bodies by considering the forces acting on them.

Rigid Body:

A Rigid Body is defined as a definite quantity of matter, the parts of which are fixed in position relative

to each other. Physical bodies are never absolutely but deform slightly under the action of loads. If the

deformation is negligible when compared to its size, the body is termed as rigid.

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Q1 : Define force?

Force is a physical quantity that changes or tires to change the state of rest or of uniform motion of an object.

Q2 : What is the different between a resultant force and equilibrium force?

Resultant Force: If a number of forces acting simultaneously on a particle,then these forces can be replaced by a single force which would produce the same effect as produced by all forces.This single force is called as resultant force. Equilibrant Force: The force which bring the set of forces in equilibrium is known as equilibrant force.It is equal in magnitude and opposite in direction of the resultant force.

Q3 : Define Coplanar & concurrent forces ?

Coplanar forces: If the line of action of all forces lie on same plane,then the forces are said to be coplanar forces. Concurrent forces: If the line of action of all forces meet at common point,then the forces are said to be concurrent forces.

Q4 : Define unit vector?

A vector having magnitude one unit is known as a unit vector .

Q5 : Differentiate between particles and rigid body?

Particle is a body which has mass but no dimension whereas rigid body as both mass and dimensions. Particle can have only translational motion where as rigid body can have translational as well as rotational motion.

UNIT-I Introduction to Mechanics27

UNIT-II Friction27

UNIT-III Centroid and Center of Gravity & Area moments of Inertia29

UNIT-IV Mass Moment of Inertia & Virtual Work19

UNIT-V Kinetics & Mechanical Vibrations23