Note: When running this simulation on a tablet or smart-phone, set the parameters, then press the Play button. When running this simulation on a computer without an accelerometer, be sure to uncheck “Accelerometer,” then set the parameters and press the Play button.

Accelerometer Calibration

The Accelerometer Calibration mobile JavaScript model is intended to show how a mobile device detects acceleration. The accelerometer reads the direction and magnitude of the proper acceleration g. An arrow shows the projection of g onto the screen and three output fields show the numerical g components. Users can tilt and shake their device and observe the change in acceleration.

Physics Exercises:

The simulation continuously displays the sensor reading when the "Accelerometer" option is selected. Data are recorded during the t=[start, end] time interval when the record button is pressed. At the end of the recording time interval, the simulation shows the components when |g| was a maximum and a minimum. The path taken by the tip of the acceleration vector is also shown.

Lock the screen orientation to maintain a fixed view as you tilt your device in the following exercises.

What are the g components when you are holding your device in "portrait" orientation? In "landscape" orientation?
What are the g components when your device is laying flat on a tabletop? How does the arrow representing g appear on the screen? Explain.
Set the start time to 2 second and the stop time to 6 seconds. Press the record button and jump off of a platform when t=4 while holding your mobile device. What are the maximum and minimum values of the acceleration components?
Caution: you must secure your device to do the following experiment. Secure your device to a rotating turntable, set appropriate start and end times, and record the acceleration as you gently spin the turntable at constant speed. Determine the location of the accelerometer within the device.
Caution: you must place your device in a padded bag to do the following experiment. Place your device to a padded bag, set appropriate start and end times, and record the acceleration as you gently swing the bag in vertical circle. What is path recorded by the tip of the acceleration vector? Repeat while swinging the bag in a horizontal circle.

Note: Continuously reading the accelerometer may drain the mobile device battery. Uncheck "Accelerometer" or navigate to a different HTML page to conserve battery power.

Teaching and Learning Objectives:

Describe the difference between proper acceleration and coordinate acceleration. How do you convert between these two types of acceleration on the surface of Earth. Hint: When is the proper acceleration zero? When is coordinate acceleration zero?
Represent a 3D vector using component notation.
Explain the common meaning of weightlessness.
Verify the mathematical relation for centripetal acceleration.