The wide-spread availability of smartphones makes them a valuable addition to the measurement
equipment of both the physics classroom and the instructional physics laboratory, encouraging an
active interaction between measurements and modeling activities. Two useful sensors, available in
most modern smartphones and tablets, are the 3-axis acceleration sensor and the 3-axis gyroscope. We
explore the strengths and weaknesses of each type of sensor and use them to study the rotational
dynamics of objects rotating about a fixed axis. Care has to be taken when interpreting acceleration
sensor data, and in some cases the gyroscope will allow for rotational measurements not easily
replicated using the acceleration sensor.