SIMPLE TRUSSES, THE METHOD OF JOINTS, &
ZERO-FORCE MEMBERS
Todays Objectives:
Students will be able to:
In-Class Activities:
a) Define a simple truss.
Check Homework, if any
b) Determine the forces in members of a
simple truss.
Reading Quiz
c) Identify

5.4 THE METHOD OF SECTIONS
Todays Objectives:
Students will be able to determine:
1. Forces in truss members using the
method of sections.
In-Class Activities:
Check Homework, if any
Reading Quiz
Applications
Method of Sections
Concept Quiz
Group Pr

6.5 PARALLEL-AXIS THEOREM FOR AN AREA &
6.6 MOMENT OF INERTIA FOR COMPOSITE AREAS
Todays Objectives:
Students will be able to:
1. Apply the parallel-axis
theorem.
2. Determine the moment of
inertia (MoI) for a
composite area.
Cross-sectional areas of stru

Todays Objective:
COMPOSITE BODIES
Students will be able to determine:
a)
The location of the center of
gravity,
b) The location of the center of mass,
In-Class Activities:
c) And, the location of the centroid
using the method of composite
bodies.
Check

6.4 - DEFINITION OF MOMENTS OF INERTIA FOR AREAS
RADIUS OF GYRATION OF AN AREA
Todays Objectives:
Students will be able to:
a) Define the moments of inertia (MoI)
for an area.
b) Determine the MoI for an area by
integration.
In-Class Activities:
Check Ho

CENTER OF GRAVITY, CENTER OF MASS AND
CENTROID OF A BODY
Todays Objective :
Students will:
a)
Understand the concepts of center of
gravity, center of mass, and centroid.
b) Be able to determine the location of
these points for a body.
In-Class Activities:

3.7 SIMPLIFICATION OF FORCE AND COUPLE SYSTEMS
& 3.8 FURTHER SIMPLIFICATION OF A
FORCE AND COUPLE SYSTEM
Todays Objectives:
Students will be able to:
a) Determine the effect of moving a
force.
b) Find an equivalent force-couple
system for a system of forc

EQUILIBRIUM OF A RIGID BODY
&
FREE-BODY DIAGRAMS
Todays Objectives:
Students will be able to:
a) Identify support reactions, and,
b) Draw a free-body diagram.
In-Class Activities:
Check Homework
Reading Quiz
Applications
Support Reactions
Free-Body D

4.3 - EQUATIONS OF EQUILIBRIUM &
4.4 - TWO- AND THREE-FORCE MEMEBERS
Todays Objectives:
Students will be able to:
a) Apply equations of equilibrium to
solve for unknowns, and,
b) Recognize two-force members.
In-Class Activities:
Check Homework, if any
R

2.5 CARTESIAN VECTORS AND
2.6 ADDITION & SUBTRACTION W VECTORS
Todays Objectives:
Students will be able to:
a) Represent a 3-D vector in a
In-Class Activities:
Cartesian coordinate system.
Reading Quiz
b) Find the magnitude and
coordinate angles of a 3-D

3.1: MOMENT OF A FORCE (SCALAR FORMULATION)
3.2: CROSS PRODUCT
3.3: MOMENT OF A FORCE (VECTOR FORMULATION), &
3.4: PRINCIPLE OF MOMENTS
Todays Objectives :
Students will be able to:
a) understand and define moment, and,
b) determine moments of a force in

6.3 REDUCTION OF A SIMPLE DISTRIBUTED LOADING
Students will be able to determine an
equivalent force for a distributed load.
In-Class Activities:
Check Homework
Reading Quiz
Applications
=
Equivalent Force
Concept Quiz
Group Problem Solving
Attenti

2.7 POSITION VECTORS
2.8 FORCE VECTORS
Todays Objectives:
Students will be able to :
a) Represent a position vector in Cartesian
coordinate form, from given geometry.
In-Class Activities:
b) Represent a force vector directed along Check Homework
a line.

2.1-2.4 FORCE VECTORS, VECTOR
OPERATIONS & ADDITION COPLANAR
FORCES
Todays Objective:
Students will be able to :
a) Resolve a 2-D vector into components.
b) Add 2-D vectors using Cartesian vector notations.
In-Class activities:
Check Homework
Reading Qu

Note: The origin (0,0,0) is located at where the ropes are
tied to the hook.
CLICKERS:
=
A) 115 deg
B) 45 deg
C) 130 deg
D) None of the
above
You must solve this problem using VECTOR ANALSYS. (You
can only use Scalar method to check your answer).
CLICKERS

3.6 MOMENT OF A COUPLE
Todays Objectives:
Students will be able to
a) define a couple, and,
b) determine the moment of a couple.
In-Class activities:
Check Homework
Reading Quiz
Applications
Moment of a Couple
Concept Quiz
Group Problem Solving
Att

If alpha=beta=gamma = 60 deg
(overstated)
and F1 = 100 N,
find the y component (only) of the Resultant force on the mast caused by F1, F2, and F3.
cos(60) =
0.5
F1x
F1y
F1z
sum(Fx)
Sum(Fy)
Sum(Fz)
50
50
50
50
-250
-150
295.803989155
for alpha
cos2(alpha)+

3.5 MOMENT ABOUT AN AXIS
Todays Objectives:
Students will be able to determine the moment of a
force about an axis using
In-Class Activities:
a) scalar analysis, and
b) vector analysis.
Check Homework
Reading Quiz
Applications
Scalar Analysis
Vector

Find the force in Member CE.
Click the Correct Answer:
A) F_CE = 1.10 kN (C)
B) F_CE = 450 N (C)
C) F_CE = 0 N
D) F_CE = 226 N (C)
Find the force in Member DE.
Click the Correct Answer:
A) F_DE = 1.20 kN (T)
B) F_DE = 1.20 kN (C)
C) F_DE = 2.10 kN (T)
D)

Did this one 10/9 5-6 pm
Did this one 10/9 5-6 pm
Did this one 10/9 5-6 pm
EGR 241 STATICS
Assignment No. 4 SOLUTIONS (contd)
Did this one 10/9 5-6 pm
Problem2
ANSWER:
A
B
Or,dowhatwedidinclassWednight
.findrABthenuABthen
letF=Fmag*uAB_x ini +Fmag*uAB_y i

Given:
A rod is supported by
smooth journal bearings
at A, B, and C. Assume
the rod is properly
aligned.
Find:
The reactions Cy and Bx.
Click the Correct Answer:
A) Cy = 813 N; BX = -932
B) Cy = -813 N; BX = 932
C) Cy = 318 N; BX = -239
D) Cy = -318 N; BX