# Conservation of energy of a rollercoaster using high speed video

This material is replicated on a number of sites as part of the SERC Pedagogic Service Project

## Summary

High speed video of a roller coaster allows students to perform careful analysis of a familiar situation.
Students use high speed video to determine whether a roller coaster is an example of a system in which mechanical energy is conserved. Students use frame counting to measure the speed of a roller coaster as it heads up a hill, and then measure the speed as the roller coaster comes back down the hill. The outcome of the measurements depends on which part of the roller coaster they measure because a motor continues to propel the roller coaster until it begins to climb the hill.

This activity follows on the activity Measuring velocity of objects using video clips.

## Learning Goals

A single frame from a video taken at 210 frames per second. Students can use the video to measure the velocity of the roller coaster at various times during the ride.

The activity is intended to give students experience extracting data from video clips, and use physics concepts and reasoning to make conclusions about the situation.

In this case, students use the video to determine the velocity of a roller coaster and apply the law of conservation of mechanical energy.

## Context for Use

This activity is intended for use in any introductory physics course. Ideally, each student should have access to a computer to complete the activity individually, but it can be done in groups or even as an interactive lecture demonstration. Although the video could be used as an introduction to the topic of conservation of mechanical energy, it is even better after students have learned the topic, so that students can apply this new concept to a real-life example.

## Description and Teaching Materials

The ride in question is called "Steel Venom," a roller coaster at Valley Fair in Shakopee MN. Included here are all the ingredients needed to use this activity.

## Teaching Notes and Tips

This activity presumes students know how to use video clips to determine the velocity of moving objects, which is covered in the activity Measuring velocity of objects using video clips.

This activity can be used in a wide variety of teaching styles. For example, the instructor can begin with a conversation about how conservation of mechanical energy applies to roller coasters and introduce the video as a conversation starter. The instructor can ask questions about the difference between an imaginary frictionless roller coaster in most textbook problems and a real roller coaster. The instructor can give the video as a challenge -- ask the students if they can develop a method to use the video to determine whether mechanical energy is conserved on this roller coaster.

For the actual analysis, students should each have their own computer. If this is not possible they can work in groups.

See a complete description of how to teach with video clips, including pedagogic strategies and a collection of sample videos.

## Assessment

Another similar activity, Conservation of energy while rolling down a hill, can be used as an assessment for this activity, or this one can be used as an assessment for that one. In addition, this activity is intended to increase student understanding of the concept of conservation of mechanical energy in general. As such, there are many existing assessments to evaluate students understanding of this topic.

## References and Resources

Steel Venom Rollercoaster - Facts and figures about the ride