Introduction To Engineering Mechanics

What is mechanics? 

Mechanics can be defined as the physical science which deals with the state of rest or motion of particles and bodies under the effect of forces.


Video on Introduction To Engineering Mechanics by Civil Stuff :-

Classification of Mechanics:-

Engineering mechanics can be broadly classified into two types, they are

1.Statics
2.Dynamics

1.Statics:-
Statics is the branch of mechanics that delas with the study of objects which are are in state of rest.

2.Dynamics:
Dynamics is the branch of mechanics that deals with the study of objects in motion and the forces causing motion or which are in motion.

• Dynamics is further classified into two main groups:

A)Kinematics
B)Kinetics

A)Kinematics:

Kinematics is the study of the motion of bodies without consideration of the cause of the motion. Kinematics deals with the space-time relationship of the motion of a body. Some examples of kinematic concepts are displacement, velocity and acceleration.

B)Kinetics:

Kinetics is the branch of mechanics which deals with the study of the motion of bodies by considering the cause of motion.

What is rigid body?

• Rigid body is the body which not undergoes any kind of deformation under the action of external forces. 
• A body is said to be rigid when the relative movements between its particle is negligible.
• But in actual practise every body deforms under the action of external forces but the deformation is negligible since it is quite small.
• Basically rigid body is body which won't be affected by the external forces and will not undergo any kind of deformation.

What is deformable body? 

• It is exactly opposite of rigid body
• Deformable body is body which undergoes deformation under the action of external forces. 
• So here we can say that there is a relative movements between the particles and which is not negligible. 

Read also- system if forces

Fundamental Concepts:-

• Space: It is a geometric region occupied by bodies whose positions are described by linear and angular measurements relative to coordinate system. 

• Time: It is a measure of the succession of events and is a basic quantity in dynamics.

• Mass: It is a measure of the inertia of a body, which is its resistance to a change of velocity.

• Force: Force is the action of one body on another. A force tends to move the body in the direction of its action. The action of a force is characterized by its magnitude, by the direction of its action and by its points of application. 

• Particle: A particle is a body of negligible dimensions.

• Scalar quantities: These are the quantities characterized by only magnitude, such as mass, temperature.

• Vector quantities: These are the quantities characterized by magnitude and direction, such as velocity, force. We will indicate vector quantities by boldfaced letters.

• Free vector: It is a vector, whose action is not confined to or associated with a unique line in space. Only, the direction and magnitude of the vector remains fixed.

• Sliding vector: It is a vector, which may be moved along the lines of action without change of meaning. For example, in towing a cart, we may apply the force anywhere along the rope. 

• Bound vector: It is a vector, which must be applied at definite point. For example, if we are interested in the deformation of body, we must be concerned with the point of application of forces.

• Concurrent forces: Two or more forces are said to be concurrent at a point if their lines of action intersect at that point.

Figure showing 4 concurrent forces in single plane:-

Concurrent force system