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.
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.
Day 2:
· 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:
· 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:
· 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:
· 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.
· 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:
· 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 4