MECHANICS
Branch of science
which deals with action(or effect) of forces on bodies.
ENGINEERING MECHANICS
Application of
principles of Mechanics to Engineering Problems.
STATICS
It deals with forces on BODIES AT REST.
DYNAMICS
It deals with
forces on BODIES IN MOTION.
KINETICS
It
is the Part of Dynamics that deals with study of motion of bodies and the forces
acting on them.
KINEMATICS
It
is the Part of Dynamics that deals with the study of motion in abstract without
reference to the cause of
motion.
1.A Physical quantity is the result of measurement and is usually
expressed as a combination of a numerical value and a physical unit.
EXAMPLE:
P = 42.3x103 = 42.3kW
With
P representing the physical quantity for power
42.3x103 being the numerical value split into
42.3 and
k, the SI prefix representing 103
W being the symbol for the unit of power, the watt
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Physical quantities are divided into
SCALAR QUANITITES
VECTOR QUANTITIES
SCALAR QUANTITIES
are quantities which have only magnitude but no direction.
Ex: Distance
Some more examples for Scalar quantities are
Speed, mass, area, volume, time, energy & density
VECTOR QUANTITES
are quantities which
possess magnitude as well as
direction.
Ex: Displacement
Here the displacement from
A to B has both magnitude and direction
Magnitude = 2m
Direction is ‘vertically
downwards’
Other Examples : velocity,
acceleration, force.
FORCE
Forceis that which changes or
tends to change the state of rest of a body or
the uniform motion of the body in a straight line
Force is a vector quantity
The unit of Force in SI system is Newton (N).
EXAMPLE
1. gravity force
2. force of magnetic attraction
3. tractive effort of a locomotive
Mathematically, Force = mass x acceleration
=
1 Kg x 1 m /sec2, in SI units
= 1
Newton
=
1(kg.m/sec2)
SYSTEM OF FORCES
Two or more forces acting
simultaneously on a body constitute a system.
Deformation & Rigid Body
Two equal and opposite forces acting along the same line nullify
each other.
As a result, the body remains in the same position.
The forces produce a change in the
shape of the body
size of the body
which is called deformation
A body not undergoing appreciable deformation under the action of
forces is called a Rigid body.
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