The mobile phone as a free-rotation laboratory

Abstract

Modern mobile phones contain a three-axis microelectromechanical system (MEMS) gyroscope, capable of taking accurate measurements of the angular velocity along the three principal axes of the phone with a sampling rate of 100 Hz or better. If the phone is tossed in the air, then, neglecting air resistance, it is in free rotation (rotation in the absence of a torque) with respect to its centre of mass, and the phone's gyroscope can be used to record the rotational dynamics. This enables experimental investigation of free rotation. In this paper, we use a mobile phone to demonstrate the steady states for rotation of the phone about two of its principal axes, and the instability in rotation about the third corresponding to the intermediate moment of inertia. We also show the approximate conservation of angular momentum and rotational kinetic energy during motion in the air, and compare the data with numerical solution of Euler's equations for free rotation. Our results demonstrate the capability of smartphones for investigating free rotation, and should be of interest to college and university teachers developing “at home” physics labs for remote learning.

Signatures of physical constraints in rotating rigid bodies

“…An interesting problem would be to observe experimentally these geometric signatures. Such measurements can be performed quite simply for standard rigid bodies such as a mobile phone [22]. Following the results established in [14], another open issue is to find geometric signatures in the Monster Flip effect, a free style skateboard trick which can be observed in the rotational dynamics of any asymmetric rigid body.…”

“…These two properties are not verified if the physical constraints are not met. On the basis of these observations, different experiments can be considered to test the physical nature of the rigid body [22]. Finally, we take advantage of this global study to extend the proof of [14] on the existence of the TRE.…”

Smartphone-based undergraduate research projects in an introductory mechanics course

“…The task idea is based on Ref. [33] and uses the idea of Ref. [34] to determine the smartphone's moment of inertia.…”

The Coriolis effect and coupled oscillations in a rotating swings amusement ride

“…Easy access to rotation sensors can help students understand the concept of rotation around different axes and opens many possibilities for education (see e.g. [18][19][20][21][22][23][24][25]).…”