BGMC 1173
STATICS
Objective
● Introduces fundamental and concepts in engineering, based on forces in
equilibrium.
○
○
○
○
○
○
force vectors
moment of a force
equilibrium of particle and rigid bodies
friction
centre of gravity
centroid and moment of inertia.
MECHANICS
● The physical science which describes and predicts the conditions of rest or
motion of bodies under the action of forces.
○ Rigid-Body Mechanics (Statics & Dynamics)
○ Deformable-Body Mechanics
○ Fluid Mechanics
Statics vs. Dynamics
1. Statics
Deals with the forces and their effects, while acting upon the bodies at rest.
1. Dynamics
Deals with the forces and their effects, while acting upon the bodies in motion. It can
be further sub-divided into :
a) Kinetics
- Deals with the bodies in motion due to application of forces.
b) kinematics
- Deals with the bodies in motion, without any reference to the forces which
are responsible for the motion.
Basic Quantities
Length: Used to locate the position of a point in space and describe the size of a
physical system.
Time: Conceived as a succession of events. Though Statics is time-independent,
time is crucial in Dynamics.
Mass: A measure of a quantity of matter that is used to compare the action of one
body with another.
Force: The "push" or "pull" exerted by one body on another. Characterized by
magnitude, direction, and point of application.
Idealizations in Mechanics
● Particle
○ A particle has a mass, but a size that can be neglected
● Rigid Body
○ Combination of a large number of particles in which all the particles remain
at a fixed distance from one another, both before and after applying a load
● Concentrated Force
○ A concentrated force represents the effect of a loading which is assumed to
act at a point on a body.
Newton’s First Law of Motion
● A particle originally at rest, or moving in a straight line with constant
velocity, tends to remain in this equilibrium state provided the particle is not
subjected to an unbalanced force
Newton’s Second Law of Motion
● A particle acted upon by an unbalanced force F experiences an acceleration a
that has the same direction as the force and a magnitude that is directly
proportional to the force
Newton’s Third Law of Motion
● The mutual forces of action and reaction between two particles are equal,
opposite, and collinear
The International System of Units (Unit SI)
Weight (W)
● Weight is the gravitational attraction of the Earth on a body located at or near
its surface.
● Formula derived from 2nd Law: W = mg
● g = acceleration due to gravity (approx. 9.81 m/s^2).
Length
Meter
m
—
Time
Second
s
—
Mass
Kilogram
kg
—
Force
Newton
N
N = (1 kg/ m/s^2)