chapter1 mechanics
DESCRIPTION
MECHANICS REVIWERTRANSCRIPT
I.
Course Outline Chapter I. Introduction
Chapter II. Force Systems
a. Coplanar
b. Non-Coplanar
Chapter III. Equilibrium of Force Systems
Chapter IV. Analysis of Structures
Chapter V. Friction
Chapter VI. Force Systems in Space
Chapter VII. Centroid and Centers of Gravity
Chapter VIII. Moment of Inertia
Mechanics is a physical science that relates the state of rest
or motion of a body subjected to external forces.
Areas (as to civil engineering study):
Rigid-body Mechanics
Deformable-body Mechanics
Fluid Mechanics
Soil Mechanics
Rigid-body Mechanics idealizes objects or any body
as non-deforming; that is, no external force causes it to
change in shape or form.
Two areas fall under rigid-body mechanics: statics and
dynamics. Statics explores the interaction of forces of
bodies at rest; comparatively, dynamics deals with bodies
under accelerated motion.
Statics
Dynamics
What is Force?
Characteristics of a Force:
1. Magnitude
2. Direction
3. Line of Action
Principle of Transmissibility
States that the conditions of equilibrium or conditions of
motion of a rigid body will remain unchanged if a force acting
at a give point of the rigid body is replaced by a force of the
same magnitude and same direction, but acting at a different
point, provided that the two forces have the same line of
action.
In other words you can resolve
a force into its components
anywhere along its line of action.
Components of a Force (Coplanar)
The axis where the force is to be resolved into should be normal
each other.
y-axis
Fy
θ=30
Fx x-axis
Example 1: Compute for the components of each of the forces shown in the figure:
y-axis
T=722 lb P=200 lb
3
2 θ=60 x-axis
2
1
F=448 lb
Example 2: The triangular block shown in the figure is subjected to the loads P= 1600lbs and F = 600lbs. If AB=8in and BC=6in, resolve each load into normal and tangential components to AC.
A
P=1600lb
C θ B
F=600lb
Multiplication Factor Prefix Symbol
x109 Giga G
x106 Mega M
x103 Kilo k
x10-3 Milli m
x10-6 Micro µ
x10-9 Nano η
x10-12 Pico p
“ Kinds of Loads ” Loads are forms of how forces occur in practice
According to geometry
1. Point Load 100N 50 lbs 10kg
2. Uniform Load 10N/m
3. Triangular Load 20lb/ft
4. Trapezoidal Load 30N/m
10N/m
Loads are forms of how forces occur in practice
According to Characterization 1. Dead Load
-dead weights of members and other fixed structures
2. Live Load
-weights which are inconsistently present or moving
3. Wind Load
- load that varies with altitude
4. Seismic Load
- load that varies with distance from active faults and tectonic activity
“ Kinds of Loads ”