In this activity, we will use the G-force detection capabilities of a standard smartphone. The accelerometer in a phone uses a small silicon chip and detects, using capacitors, the motion of this chip relative to the housing of the phone. This allows the phone to know what orientation the phone is in relative to the surface of the Earth, and change the orientation of the phone's display accordingly. It also allows some fun with physics!
A free app called Physics Toolbox by Vieyra Software takes data from the phone's accelerometer and graphs it over time. With this data made available using the average smartphone, a wide range of exploration and experimentation are now possible with a device that most students habitually carry around in their pocket.
For this activity, we'll use the Physics Toolbox interface to have some fun with orientation and movement in space.
1. In the reference frame of the phone, which direction corresponds to which Cartesian component? For example, does the top of the phone point in the positive or negative x, y, or z-component? Does this change if the phone is rotated?
2. Can you make your graph look something like this picture? (Include only the green and blue line in the Physics Toolbox display)
- Can you keep the total g-force (white line) above 1 for longer than a few seconds?
Here are some labs where the primary data collection and recording are done using Physics Toolbox, made available on www.vieyrasoftware.net:
“Identifying Gait Metrics”
"Exploring Three-Component Seismic Data with Accelerometers"
"How Hard Does the Ground Shake During an Earthquake?"
“Measuring height in an Elevator ride”