Everyone already knows that you are carrying around a computer in your pocket. But your smartphone is more than just a computer—it's also a data collector. I'm going to guess that yours can measure acceleration, magnetic field, sound, location, and maybe more. Many phones also can measure pressure. Oh, and some phones can even make phone calls.

With all of those sensors available, I'm going to go over three fun experiments you can do with your phone. These will probably work on just about any smartphone—and you can probably use a variety of apps to collect the data. For these examples, I'm going to stick with phyphox (http://phyphoxorg). There have been lots of data collecting apps—but this one is the best I've seen lately. Also, it's free and runs on both iOS and Android. Check it out.

Bouncing Ball

Get a small ball—actually, the size doesn't really matter. There are only two things that the ball needs to do for this experiment: It needs to bounce and it needs to make a noise when it hits the table (or whatever surface it hits). That's it. Now start up your phyphox (pronounced fi-fox) app and open up the experiment file "(In)elastic collision." Place your phone near the location that the ball will hit the surface so that the microphone can pick up the sound. Start recording and drop the ball.

The app then records all of the times the ball hits the ground. It's pretty cool. The app also uses the time between bounces to calculate the bounce height (I suppose the calculation assumes you are on the surface of the Earth with a vertical acceleration of 9.8 m/s2).

Just for fun, here is a plot of bounce height vs. bounce number for a small metal ball bouncing on my lab table.

But now that data is super simple to collect—you can explore the relationship between initial drop distance and bounce height for a wide variety of balls. What changes for each successive bounce? Does it lose the same height or the same energy? In case you are curious, this is something I looked at some time ago (more details).

Measuring the Speed of Sound

Although it's fun to come up with your own experimental method to determine the speed of sound—here is a method that works fairly well using two smartphones. You need to run something that will act as an acoustic stop watch (phyphox has one). The acoustic stop watch is just like a normal timer. The only difference is that it starts and stops the timing based on a loud sound—like a clap.