Overview

In this activity, students will be using the Tracker software to analyze conservation of energy in projectile motion. (Example of Video analysis and modeling tool - Tracker software)

In groups of 3-4, students go outdoors and take a video of themselves throwing an object, being careful to frame the video correctly and to include some means of distance calibration (such as a meter stick), and ensuring the camera does not move while they film. This can be done using a cell phone.

Students then return to a computer ...

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In this activity, students will be using the Tracker software to analyze conservation of energy in projectile motion. (Example of Video analysis and modeling tool - Tracker software)

In groups of 3-4, students go outdoors and take a video of themselves throwing an object, being careful to frame the video correctly and to include some means of distance calibration (such as a meter stick), and ensuring the camera does not move while they film. This can be done using a cell phone.

Students then return to a computer or interactive whiteboard and upload this video into the Tracker software (for example by emailing themselves the video), and calibrate the axes and distances. They then track the object frame by frame as a point mass using the software, which uses this data to produce tabulated data for position, velocity, and acceleration along both axes. Students export this data.

Working alone with a computer (or in pairs if computers are limited), students import the data into a spreadsheet program such as Excel. Students create columns for potential energy, kinetic energy, and total energy, then use spreadsheet formulas to populate these columns. Students plot all three on the same graph in their spreadsheet program.

Students then return to their original groups to compare their resulting plots and discuss the implications. If energy was not constant over time, they can discuss where energy was lost.

Finally, the instructor can lead a class discussion of the results and conservation of energy.

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Objectives

Students learn to analyze data using spreadsheet programs and gain a deeper understanding of conservation of energy.

Context and requirements

Level Grade 12-U0
Discipline Physics
Course Mechanics
Activity Content Energy Conservation, Potential/Kinetic Energy
Technological Requirements Computers or interactive whiteboards with Tracker software are required, as is excel. Students will also need to take a video with their phone and access it with the computer (for example by email).
Best Use Practice, Review

Author’s Notes

Benefits

Students learn to analyze and plot data and learn to work with spreadsheets, including using formulas and plotting.

Students begin to appreciate that the equations of conservation of energy don’t come from nowhere, for example that each term has a role in making the big picture true.

Challenges

One challenge to this activity is that it has dependencies on several technologies, and it is therefore important to test everything beforehand. You should test your workstations, making sure you can take a video with your phone and get it onto the stations where students are working, then upload it into the motion tracker.

The slow motion function on the motion tracker is tempting to use, but the algorithm behind it currently has bugs relating to the logged time difference – it should therefore be avoided.

Tips

It’s very important to get as many students as possible working hands-on with a computer in the spreadsheets portion, otherwise the student with the most computer knowledge is likely to take over. If possible, each student should have a computer, if not then students should be in pairs at the most.

Visual classrooms makes a great platform to upload and share documents into for this activity.

If students use a very large object, they may be confused as to what part of it to track. This can be a “teachable moment”, as they should use the center of mass.

It is useful to pair this with the Projectile Tracker activity earlier in the year, as students will then already be comfortable with the Tracker software and can therefore spend more time working with spreadsheets.

Activity Pedagogical Components

Data Collection

Working in GROUPS, students go outdoors to take a video of themselves throwing an object (projectile motion). This video is taken such that it includes a calibration tool. This work is done IN CLASS (during class time).

Data Analysis

Working in GROUPS, students use the Tracker software to analyze their data, creating tabulated data for the position and velocity over time. This is done IN CLASS.

Data Analysis

Working INDIVIDUALLY, students import the data into Excel and use spreadsheet formulas to create data for potential, kinetic, and total energy. Students plot this data. This is done IN CLASS.

Peer Review

Students return to their original GROUPS, comparing their plots and discussing the implications regarding conservation of energy. This is done IN CLASS.

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