APPLIED MECHANICS : BASIC CONCEPTS

 DEPARTMENT OF MECHANICAL ENGINEERING  

      APPLIED MECHANICS/BASIC CONCEPT

Motion: When the position of a body changes with respect to its surroundings, the body is said to be in motion.

Rest: When a body does not change its position with respect to its surroundings, it is said to be in rest.

Rest and motion are relative terms.

Physical Quantities: All the quantities in terms of which laws of Physics are described and whose measurement is necessary are called physical quantities.

Scalar Quantities: Any physical quantity which can be completely specified by its magnitude alone, is a scalar quantity.

Vector Quantities: Any physical quantity which requires direction in addition to its magnitude, is known as a vector quantity.

Distance: The length of the path travelled by a body in a certain interval of time is known as distance.

Displacement: The shortest distance between the initial and final positions of a body is known as displacement.

Speed: It is the distance travelled by the body along a straight line or curved path per unit time.

Velocity: Velocity is defined as change of position of a moving body in a definite direction per unit time or the distance travelled by the moving body per unit time in a given direction.

Acceleration: The rate of change of velocity of a moving body with time is called acceleration.

Mass: The mass of a body is the quantity of matter (material) contained in it.

Force: A force may be defined as an external cause which changes or tends to change its state of rest, or of uniform motion, direction of motion, or shape of the object.

Momentum: Momentum of a body is the product of its mass and velocity.

Impulse: The impulse acting on a body is defined as the product of force acting on the body and time taken for which it acts.

Inertia: Inertia is inability of a body to change by itself.

Friction: Friction is the force which always opposes the motion of one body over another body in contact with it.

Gravitation: Gravitation is the name given to the force of attraction acting between any two bodies in the universe.

Gravity: It is the force of attraction exerted by earth towards its centre, on a body lying on or near the surface of earth. It is the measure of weight of the body.

Acceleration Due To Gravity: It is defined as the acceleration set up in a body while falling freely under the effect of gravity alone.

Work: Whenever a force acts on a body and moves it in its direction, work is said to be done by the force and is measured by the product of the force and the displacement in the direction of force.

Power: Power is defined as the rate of doing work.

Energy: The capacity of doing work is called energy.

Space: It is a region which extends in all directions in the universe and contains everything in it. The position of a point in space is defined by some frame of reference and coordinate system. In order to define the state of rest or of motion of a body , some datum or reference is required.

Time: It is a measure of succession of events.

Matter: It is anything that occupies space and has physical existence.

Particle: It is defined as an object whose mass is concentrated at a point.

Body: A body is a portion of matter which occupies finite space and consists of number of particles.

Rigid Body: A rigid body is that which does not change its shape or size when subjected to external forces.

Applied Mechanics: The science which deals with the physical state of rest or of motion of rigid bodies under the action of external forces, when applied to engineering problems is termed as Applied Mechanics.

Characteristics of A Force:

1. Magnitude                                   2. Direction

3. Point of Application                  4. Line of Action