The gyroscope in a smartphone was employed in a physics laboratory setting to verify the conservation of angular momentum and the nonconservation of rotational kinetic energy. As is well-known, smartphones are ubiquitous on college campuses. These devices have a panoply of built-in sensors. This creates a unique opportunity for a new paradigm in the physics laboratory.1–3 Many traditional physics experiments can now be performed very conveniently in a pedagogically enlightening environment while simultaneously reducing the laboratory budget substantially by using student-owned smartphones.

If you take a video of the event, it may show that there is a slight counterclockwise tipping of the body in Fig. 1 just before the tape is pulled completely inside. Discuss with students how this motion is related to the decreasing moment of inertia of the extended part of the tape around the axis of the return mechanism.
As with the first activity, there is a slight counterclockwise rotation in Fig. 3 just before the tape is pulled completely inside.
“Energy and the confused student IV: A global approach to energy,”
Phys. Teach.
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