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MECHANICS REVIWER

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Page 1: Chapter1 MECHANICS
Page 2: Chapter1 MECHANICS

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

Page 3: Chapter1 MECHANICS

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

Page 4: Chapter1 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.

Page 5: Chapter1 MECHANICS

Statics

Page 6: Chapter1 MECHANICS

Dynamics

Page 7: Chapter1 MECHANICS

What is Force?

Characteristics of a Force:

1. Magnitude

2. Direction

3. Line of Action

Page 8: Chapter1 MECHANICS

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.

Page 9: Chapter1 MECHANICS

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

Page 10: Chapter1 MECHANICS

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

Page 11: Chapter1 MECHANICS

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

Page 12: Chapter1 MECHANICS

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

Page 13: Chapter1 MECHANICS

“ 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

Page 14: Chapter1 MECHANICS

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 ”