Introduction to Dynamics
Text Book:
Introduction to Dynamics
Mechanics
Statics
Dynamics
Mechanics is a branch of the physical sciences that is concerned with the state of rest or
motion of bodies subjected to the action of forces.
Dynamics
Kinematics
Kinetics
kinematics, treats only the geometric aspects of the motion whereas kinetics is involved
in the analysis of the forces causing the motion
The beginning of a rational understanding of Dynamics is credited to Galileo Galilei (1564-1642) who
made careful observations concerning bodies in free fall, motion on an inclined plane and motion of the
pendulum.
The most significant contributions in dynamics, however, were made by Isaac Newton (1642–1727), who
is noted for his formulation of the three fundamental laws of motion and the law of universal
gravitational attraction.
All the calculations we do in dynamics today are based on these three fundamental laws established by
Isaac Newton. After Newton the contributions were mostly made in the field of developing techniques
related to solution of problems.
1st law
In an inertial frame of reference, an object either remains at rest or continues to move at a constant
velocity, unless acted upon by a force.
2nd law
In an inertial frame of reference, the vector sum of the forces F on an object is equal to the mass m of
that object multiplied by the acceleration a of the object: F = ma. (It is assumed here that the mass m is
constant – see below.)
3rd law
When one body exerts a force on a second body, the second body simultaneously exerts a force equal in
magnitude and opposite in direction on the first body.
Time is a measure of the
succession of events and
is considered an absolute
quantity
Space is the geometric region
occupied by bodies.
We use a reference system for
determining the position in space
by making linear or angular
measurements
Mass is quantitative
measure of inertia or
resistance to motion.
Force is any interaction
that, when unopposed,
will change the motion of
an object
SI Units (International System of metric units)
Dimensional Symbol
Unit Symbol
Mass
M
kg
Length
L
m
Time
T
s
Force
F
N
Actually F is not a dimension on its own it is related to the other dimensions in the table above by Newton’s 2nd
LAW
F=m a
[F]=[M][L]/[T]2
Speed=distance travelled [L]/time [T] it’s unit is m/s in SI
GRAVITATON
N=kg.m/s2