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# Student Analysis of a Cart Rolling Down a Ramp

#### Summary

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In this activity students use technology to investigate conservation of energy, Hooke's Law, and transfers of energy. Students will use previous knowledge of Hooke's Law, but will be using simulations on PhET Colorado's website to analyze energy conservation. Ultimately, students will be using a video and taking direct measurements to analyze energy conservation. Their final analysis on the video will provide a topic for further discussion on energy lost to friction.

## Learning Goals

Students will:

• Develop open-ended problem solving skills
• Compare and contrast kinetic energy, elastic potential and gravitational potential energy
• Explore a simulated version of a system that demonstrates conservation of energy, and compare it to a video of a real-world system.
• Apply the law of conservation of energy to a simulated system (PhET) and real system (Direct Measurement Video).
• Calculate spring constants using Hooke's Law
• Analyze videos through direct measurement to calculate spring constants and relative change in potential energy

## Context for Use

This lesson would be used during the energy conservation unit in a general physics course. After introducing mechanical energy, both kinetic and potential, a focus can be placed on the energy conservation portion. An introduction to Hooke's law may be necessary. It is assumed that students have had prior experience using direct measurement videos. If they have not, then the activity Introduction to Using Direct Measurement Video: Determine the speed of a Roller Coaster would be a useful introduction.

## Description and Teaching Materials

Essentially, this lesson is a one class period lesson that utilizes technology for almost the entire period. Students will be exploring Hooke's Law, mechanical energy, thermal energy, and connections between both of the previous concepts with conservation of energy.

There is an additional handout available for students to use as a general guide along with assessment questions along the way.
Instructions that accompany Video Analysis - Cart Rolling Down a Ramp (Microsoft Word 2007 (.docx) 815kB Jul13 12)

In this handout, students are instructed to follow the simulations through PhET Colorado's website (links provided on document) and complete the assigned calculations and explanations.

At the end of the handout, students will use direct measurement in the video of "Cart Rolling Down Ramp" (see resources section for link to video). Portions of this are intentionally left open-ended. Students will ideally be placed into groups of 2-4 students to collaborate to develop methods they will need to solve for the spring constant. If teachers want to simplify this process, they can discuss with their students which equations would be appropriate for the direct measurement video (Peg = PEspring;mgh = 1/2 kx2). In addition, the teacher could also discuss the conceptual idea behind solving for the spring constant.

The web page for this video contains all the available file types for this video and contains videos for shallow, medium, and steep ramps.

Students can access this video via the student video library which allows access to all videos for students, without links to instructor materials.

## Teaching Notes and Tips

Allow students ample time to explore the simulations without asking them to answer specific questions. They should spend a little bit of time getting to know what each simulation can do.

Make sure students download the video to their computer and view is using QuickTime viewer to view the video frame-by-frame to collect data.

## Assessment

At the end of this lesson, students will need to turn in the answers to the questions on the accompanying document. A quick formative assessment of this lesson will be based on their analysis of the direct measurement video and explanation of the conservation of energy (or lack thereof).

Within the document includes direct measurement calculations both on the simulations and the SERC video.

A summative assessment will be given at the end of the unit in which students will have to solve calculations similar to the ones calculated in the direct measurement video.

## References and Resources

The web page for this video contains all the available file types for this video and contains videos for shallow, medium, and steep ramps.

Instructions that accompany Video Analysis - Cart Rolling Down a Ramp (Microsoft Word 2007 (.docx) 813kB Jul10 12)
This is the file I created to accompany the "Cart Rolling Down Ramp" video.