Harnessing the power of a smartphone barometer for physics lessons

Smartphones contain powerful sensors that help measure and record the world around them. For instance, many smartphones contain a barometer sensitive enough to tell pressure differences between different elevations on a staircase. Barometers in wearable devices are used to alert emergency services if a device holder suddenly falls and can be combined with other sensors to count steps.

Leland Aldridge and Ananda Shastri utilized these instruments to teach a college-level physics principle, Stevin’s Law.

Shastri compared Stevin’s Law to a game of telephone, in which a word or phrase is passed from person to person to see how it will distort over time.

“When you put a gas in a gravitational field, each layer of the gas is falling in gravity, and when you look at the combined impact of each layer falling [and colliding with molecules in the layer below it] … you find that the deeper you are in the gravitational field, the higher the pressure is,” Shastri said. “It’s kind of like this game of telephone but applied in a gravitational field.”

Utilizing the Physics Tools application, which allows users access to a smartphone’s barometer and accelerometer, students can observe pressure changes while performing actions like stepping up and down a ladder.

In another part of the experiment, students can use a device to explore the pressure in a rotating cylinder, which creates a type of artificial gravity. By graphing the data, the students can compare the equations derived from their smartphone experiments to the ones derived from Stevin’s Law.

While Shastri has not yet implemented the lesson in his classroom, he is currently working on fitting it into his university’s physics curriculum.

Source: “Using a smartphone to explore fluid pressure dependence on position and acceleration,” by Leland Aldridge and Ananda Shastri, The Physics Teacher (2025). The article can be accessed at https://doi.org/10.1119/5.0215168 .