Hands-on Activity: Using Hooke's Law to Understand Materials
Educational Standards :
Pre-Req Knowledge (Return to Contents)
Students should have familiarity with algebra and be able to solve algebraic equations. They should also have experience graphing data using Microsoft Excel.
Learning Objectives (Return to Contents)
After this activity, students should be able to:
Materials List (Return to Contents)
Each group needs:
To share with the entire class:
Introduction/Motivation (Return to Contents)
For the design project we're working on for this course, we must come to understand how the materials in our bodies behave in response to forces so that we can design biomedical devices that do not harm the body.
The first step towards understanding tissue behavior is to learn how elastic solids respond to forces. To illustrate the concepts that we will learn in the solid mechanics lesson, let's first explore how springs behave, since they are often used to model elastic solid behavior. Most of the materials available to build your devices are also characterized as elastic solids. Therefore, we need to obtain an understanding of how they behave in response to forces so that we can select materials accurately in order to create successful engineering designs.
Vocabulary/Definitions (Return to Contents)
Procedure (Return to Contents)
(optional: Show students the attached four-slide Hooke's Law Presentation PowerPoint to accompany the activity described below.)
Begin by conducting this activity, then proceed to conduct the associated lesson. Students benefit significantly by completing the activity first because the lesson material is so new and different than anything they have done before and so it helps to have the hands-on reference of what they learned in the activity while learning the theory. We found that when the lesson was taught first, students were completely lost and did not grasp the concepts nearly as well as when the activity was completed first.)
Springs behave as described by Hooke's law, which states that the extension or compression (that is, displacement) of a spring, x, is directly proportional to the force applied to the spring, F. The proportionality constant of this relationship is termed the spring constant, k, and can be thought of as the stiffness of the spring.
F = kx
In today's activity, we use Hooke's law to calculate the spring constant of multiple springs. The two variables needed in the above equation are F and x, so we need to record the resulting displacement when a known force is applied to a spring.
Before the Activity
With the Students
Attachments (Return to Contents)
Troubleshooting Tips (Return to Contents)
To reduce time and cost, this activity can be completed using a minimum of two springs of differing stiffness for each group.
Assessment (Return to Contents)
Spring Observations & Stiffness Predictions: After students collect team supplies ask them to note (in a lab notebook or paper) any similarities or differences between the springs. Are they physically different? Do they feel different? Do you expect them to have the same stiffness? If not, list the springs in order from stiffest to most compliant.
Activity Embedded Assessment
Revisit Predictions: After students have collected all their data, have them revisit their predictions of whether they thought the springs have the same stiffness or not. Ask them to describe whether they still think their predictions are correct or not, and why. If they think that their predictions were incorrect, then note how their predictions changed. If they think the stiffness differs, then put the springs in order from stiffest to most compliant.
Worksheet: Assign students to complete the Hooke's Law Data Analysis Worksheet. Review their answers to gauge their mastery of the subject matter.
ContributorsBrandi N. Briggs, Marissa H. Forbes
Copyright© 2011 by Regents of the University of Colorado.
Supporting Program (Return to Contents)Integrated Teaching and Learning Program, College of Engineering, University of Colorado Boulder
Acknowledgements (Return to Contents)
The contents of these digital library curricula were developed by the Integrated Teaching and Learning Program under National Science Foundation GK-12 grant no. 0338326. However, these contents do not necessarily represent the policies of the National Science Foundation, and you should not assume endorsement by the federal government.