Lesson 2.1 Statics
Note: Career Exploration - students will continue to explore careers related to
engineering and engineering technology by completing the activity Career Field
Description. Students will decide upon a specific career field of interest to explore
and research. Students will create a comprehensive description of their chosen
career field. The description will contain information ranging from career-related
responsibilities to working conditions. The Career Field Description activity should be
completed during Unit 2 and submitted to the course instructor at the completion of
Lesson 2.4.
Preface
Statics is the basis for the study of engineering mechanics and specifically rigid-body
mechanics. Statics is concerned with the equilibrium of bodies that are at rest or that
move at a constant velocity. Using measurements of geometry and force,
Archimedes studied statics concepts in ancient Greece. Most of his work centered
on simple machines for construction of buildings.
In this lesson students will learn how to identify and calculate forces acting on a
body when it is in static equilibrium. Students will calculate internal and external
forces of a truss. They will use this knowledge to design, build, and test their own
truss designs.
Understandings
1. Laws of motion describe the interaction of forces acting on a body.
2. Structural member properties including centroid location, moment of inertia, and
modulus of elasticity are important considerations for structure design.
3. Static equilibrium occurs when the sum of all forces acting on a body are equal to
zero.
4. Applied forces are vector quantities with a defined magnitude, direction, and
sense, and can be broken into vector components.
5. Forces acting at a distance from an axis or point attempt or cause an object to
rotate.
6. In a statically determinate truss, translational and rotational equilibrium equations
can be used to calculate external and internal forces.
7. Free body diagrams are used to illustrate and calculate forces acting upon a
given body.
© 2012 Project Lead The Way, Inc.
Principles of Engineering Lesson 2.1 Statics – Page 1
Knowledge and Skills
It is expected that students will:
 Create free body diagrams of objects, identifying all forces acting on the
object.
 Mathematically locate the centroid of structural members.
 Calculate moment of inertia of structural members.
 Differentiate between scalar and vector quantities.
 Identify magnitude, direction, and sense of a vector.
 Calculate the X and Y components given a vector.
 Calculate moment forces given a specified axis.
 Use equations of equilibrium to calculate unknown forces.
 Use the method of joints strategy to determine forces in the members of a
statically determinate truss.
Essential Questions
1. Why is it crucial for designers and engineers to construct accurate free body
diagrams of the parts and structures that they design?
1. Why must designers and engineers calculate forces acting on bodies and
structures?
2. When solving truss forces, why is it important to know that the structure is
statically determinate?
National and State Standards Alignment
Please visit the PLTW Standards and Objectives Tool for the most up-to-date Standards
Alignment at http://alignment.pltw.org
Day-by-Day Plans
Time: 14 days
NOTE: In preparation for teaching this lesson, it is strongly recommended that the
teacher read the Lesson 2.1 Teacher Notes.
Day 1:
 The teacher will distribute and explain Career Field Description and Career
Field Description Rubric.
 The teacher will lead a discussion about how to obtain information relating
to engineering and engineering technology career fields. Students will be
given a due date for the activity to be completed and submitted.
 The teacher will present Concepts, Key Terms, and Essential Questions to
provide a lesson overview.
 The teacher will deliver Introduction to Statics.ppt.
 Students will take notes during the presentation in their journals.
 Optional: The teacher may want to distribute Lesson 2.1 Key Terms
Crossword for homework once the key terms have been introduced.
© 2012 Project Lead The Way, Inc.
Principles of Engineering Lesson 2.1 Statics – Page 2
Day 2:
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The teacher will deliver Centroids.ppt.
Students will take notes during the presentation in their journals.
The teacher will distribute, explain, and assign Activity 2.1.1 Centroids.
Optional Activity – Students can complete MDSolids Animated Learning
Tools – Section Properties 2.1 Centroids: Ropes and/or Section Properties
2.2 Centroids: Master of the Realm. 1-2 class periods will be needed to
complete both activities.
Day 3:
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The teacher will review and collect Activity 2.1.1 Centroids.
The teacher will deliver Introduction To Structural Member Properties.ppt
Students will take notes during the presentation in their journals.
Optional Activity – Students can complete MDSolids Animated Learning
Tools – Section Properties 2.3 Inertia: Square One. One class period will be
needed to complete the activities.
 The teacher will distribute Activity 2.1.2 Beam Deflection.
 Students will complete Activity 2.1.2 Beam Deflection while the teacher
leads the class through the activity.
 Students will complete Activity 2.1.2 Beam Deflection calculations and
conclusion questions individually for homework.
Day 4:
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The teacher will review and collect Activity 2.1.2 Beam Deflection.
The teacher will deliver Free Body Diagrams.ppt.
Students will take notes during the presentation in their journals.
The teacher will distribute, explain, and assign Activity 2.1.3 Free Body
Diagrams.
Day 5:
 The teacher will review and collect Activity 2.1.3 Free Body Diagrams.
 The teacher will deliver Force Vectors.ppt.
 Students will take notes during the presentation in their journals.
 The teacher will distribute, explain, and assign Activity 2.1.4 Calculating
Force Vectors.
Day 6:
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The teacher will review and collect Activity 2.1.4 Calculating Force Vectors.
The teacher will deliver Moments.ppt.
Students will take notes during the presentation in their journals.
The teacher will distribute Activity 2.1.5 Calculating Moments.
Students will complete Activity 2.1.5 Calculating Moments while the teacher
leads the class through the activity.
 Students will complete Activity 2.1.5 Calculating Moments calculations and
conclusion questions individually for homework.
Day 7:
 The teacher will review and collect Activity 2.1.5 Calculating Moments.
© 2012 Project Lead The Way, Inc.
Principles of Engineering Lesson 2.1 Statics – Page 3
 The teacher will deliver Calculating Truss Forces.ppt.
 Students will take notes during the presentation in their journals.
 The teacher will distribute and explain Activity 2.1.6 Step-by-Step Truss
System.
 The teacher will begin the activity by guiding students through the activity
procedure and steps.
Day 8:
 Students will continue to work on Activity 2.1.6 Step-by-Step Truss System.
 The teacher will review and collect Activity 2.1.6 Step-by-Step Truss
System.
 The teacher will distribute and explain Activity 2.1.7 Calculating Truss
Forces.
Day 9:
 VEX platform:
 The teacher will distribute Project 2.1.8 Truss Design (VEX), and
students in teams of two or three will build trusses as outlined in the
activity.
 For each set of eight students, a truss testing device should be built
using Truss Tester Build Instructions (VEX).pdf and Truss Testing
Procedure (VEX) in order for them to test their trusses.
 SSA with Truss Tester:
 The teacher will distribute Project 2.1.8 Truss Design (SSA), and
students in teams of two or three will build trusses as outlined in the
activity and test them the following day using the SSA and
matching Truss Testing device.
 Students will allow their trusses to dry before the next class session.
 Students will continue work on Activity 2.1.7 Calculating Truss Forces while
the instructor provides necessary guidance.
Day 10:
 Students will test their truss designs and complete required documentation
in their engineering journals.
 As teams take turns testing their designs, students will continue work on
Activity 2.1.7 Calculating Truss Forces. The instructor will provide
necessary guidance.
Day 11:
 The teacher will lead a discussion to define the constraints and
expectations for the Truss Design Challenge portion of Project 2.1.8 Truss
Design.
 Students will record the necessary information in their engineering
notebooks.
 Students will begin designing and evaluating their design ideas.
 Students will complete the calculations for Activity 2.1.7 Calculating Truss
Forces as homework.
Days 12 - 14:
© 2012 Project Lead The Way, Inc.
Principles of Engineering Lesson 2.1 Statics – Page 4
 The teacher will review and collect Project 2.1.7 Calculating Truss Forces.
 Students will finish designing, building, testing, and preparing
documentation for the Truss Design Challenge portion of Project 2.1.8
Truss Design.
© 2012 Project Lead The Way, Inc.
Principles of Engineering Lesson 2.1 Statics – Page 5