Learning Activity

Rubber Band Force

Subject Area

Science

Grade(s)

8

Overview

This learning activity should be used during a lesson on using models to construct an explanation of how the force exerted by a rubber band changes as the band is stretched.  This learning activity can be used as an assessment.

This activity results from the ALEX Resource Development Summit.

Science (2015) Grade(s): 8

SC15.8.14

Use models to construct an explanation of how a system of objects may contain varying types and amounts of potential energy (e.g., observing the movement of a roller coaster cart at various inclines, changing the tension in a rubber band, varying the number of batteries connected in a series, observing a balloon with static electrical charge being brought closer to a classmate’s hair).

Unpacked Content

UP:SC15.8.14

Vocabulary

  • Model
  • System
  • Potential energy
  • Force
  • Electric force
  • Magnetic force
  • Gravitational force

Knowledge

Students know:
  • Potential energy is stored energy.
  • When two objects interact a distance, each one exerts a force on the other that can cause energy to be transferred to or from an object. The exerted forces may include electric, magnetic, or gravitational forces.
  • As the relative position of two objects (neutral, charged, magnetic) changes, the potential energy of the system (associated with interactions via electric, magnetic, and gravitational forces) changes.
  • Elastic potential energy is potential energy stored as a result of work done to an elastic object, such as the stretching of a spring. It is equal to the work done to stretch the spring, which depends upon the spring constant k as well as the distance stretched.

Skills

Students are able to:
  • Use a model of a system containing varying types and amounts of potential energy and identify the relevant components.
  • Describe the relationships between components of the model.
  • Articulate a statement that relates a given phenomenon to a scientific idea, including how a system of objects may contain varying types and amounts of potential energy.

Understanding

Students understand that:
  • The types of potential energy in a system of objects may include electric, magnetic, or gravitational potential energy.
  • The amount of potential energy in a system of objects changes when the distance between stationary objects interacting in the system changes because a force has to be applied to move two attracting objects farther apart, or a force has to be applied to move two repelling objects closer together, both resulting in a transfer of energy to the system.

Scientific and Engineering Practices

Developing and Using Models

Crosscutting Concepts

Systems and System Models

Phase

During/Explore/Explain
Learning Objectives

Learning Objectives

I will use a model to explain the relationship between the force of a rubber band and the amount it stretches.

I will analyze a chart to determine the stretch versus the force of a rubber band. 

Activity Details

How is the force of a rubber band changed as the rubber band is stretched?

  1. Pass out Student Sheet.
  2. Students will place a rubber band around one of the meter sticks and move it to the middle of the meter stick.
  3. Students will then place the meter stick with the rubber band around it on the floor or along the edge of a lab table.
  4. On both ends of the meter stick with the rubber band around it, two students will need to anchor down the meter stick so that it does not move. (If the students tape the meter stick down, they may not need to anchor the meter stick down.)
  5. Students will then place the second meter stick on the floor or along the edge of a lab table so it is perpendicular to the meter stick with the rubber band around it. (Students may need to tape down the meter stick with the rubber band around it to the floor or table to ensure it does not move during the activity.)
  6. Students will hook a spring scale to the free end of the rubber band. (The rubber band should be laying flat and not stretched at the beginning of the activity.)
  7. One student will pull the spring scale in order to observe and record the spring scale’s force reading on the Student Sheet.
  8. Repeat stretching the rubber band and recording the reading for each additional 4.0 cm shown on the worksheet.
  9. Students will answer questions from Assessment Strategies to check for understanding.
Assessment Strategies

Assessment Strategies

Determine if the students understand the relationship between the force of the rubber band and the amount it stretches by using the following open-ended questions (the following questions are on the Student Sheet):

  1. What does your chart tell you about the relationship between force needed to stretch the rubber band and the distance it stretches? The force exerted on the rubber band increases as the rubber band was stretched.
  2. Did the force needed to stretch the rubber band increase by the same amount each time it stretched an additional 4.0 cm?  Answers will vary due to the elasticity of the rubber bands.
  3. What is the effect of increasing the stretch of a rubber band on its elastic potential energy? As the rubber band is stretched the elastic potential energy increases.

Background and Preparation

Background / Preparation

The teacher should gather the following materials to complete this learning asset:

  1. Students will need to be placed in groups of three to four
  2. Print Student Sheet and copy one per student
  3. 2 Meter sticks
  4. Spring Scale
  5. Rubber Band (small rubber bands work best)
  6. Masking Tape

Digital Tools / Resources

Rubber Band Force
https://docs.google.com/document/d/1qrdudGVUH9SnkGJQ_d1KWFDh9raow9ZgKKL30drNLo8…

Approved Date

Owner (Author)

yvetteakridge
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