Physics Class, Measuring Motion, and the Video Physics iPad App

Teachers can use iPads in their physics classrooms to encourage students to apply mathematical concepts to real world examples. The Video Physics iPad app enables physics students to capture video of an object in motion, and to use this data to help measure its velocity.

In this activity, physics students measure the loss of energy in a spring over time using the Video Physics iPad app, and a PASPORT AirLink and PASPORT Accelerometer.

Calibrate spring length with Video Physics for iPad
Submitted by Dr. Randy Yerrick, professor of science education, State
University of New York at Buffalo
Grade level 9th- to 12th-grade math or physics
Objectives Students create a mathematical model for physical phenomenon
and apply their conceptual understanding of trigonometric functions
and physics to explain how a spring loses energy over time.
Apps/tools iPad 2 (or higher), iOS 5.1 (or higher), Video Physics app by
Vernier, Data Analysis app or Numbers app
Materials needed A weight attached to a large spring

Hang a weight from a large spring from the ceiling or ring stand. Be sure there is a meter-stick near the spring to calibrate the spring length.

To do the extension activity simultaneously, hang the PASPORT AirLink and Accelerometer from the end of the spring.

Ask the students to use their iPad to predict the shape of the graph of a y distance per time for the oscillating spring. Once the students’ ideas have been made public and debated, pull down the spring, release, and begin the experiment.

The spring should have just enough tension to give a large amplitude but not enough to cause jumping or erratic motion outside the up and down y-axis.

Students collect the video through the camera app. This can also be done with the Video Physics app using the New Video Capture function. The video will be analyzed for its motion over time.


Once the video collection is stopped, open the video in the Video Physics app; set the scale for the meter-stick length’ and tap the position of the Airlink, marking the position with a dot every tenth of a second automatically. Each tap will create a y versus t graph and also automatically advance the frame.

Swipe to the next screen after data collection is finished. Examine the previous predicted models, and compare them with the actual data.

Export data to the Data Analysis or Numbers app, and find a best fit for the collected data.