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This document explores the experimental and theoretical aspects of a magnetically coupled oscillator system with two swinging magnets. The setup is designed to allow for long-lasting oscillations and is cost-effective by utilizing a smartphone magnetometer to measure the dipole moment of the magnet and record the period of the oscillations. The document discusses various setups and approaches used in studying magnetically coupled oscillators, and presents a simplified setup that uses a low-friction pivot and a smartphone for data recording. The physical setup, theoretical model, and experimental results are described in detail. The document concludes by suggesting that this setup can be a valuable addition to existing experiments on coupled oscillators. [Extracted from the article]

This article presents a study on the temperature-dependent sound speed in a beaker using a smartphone. The researchers conducted experiments with a tall beaker and a smartphone to measure the frequency and harmonics of the sound produced as the beaker was filled with water. They also investigated how the speed of sound changed as the air inside the beaker became warmer. The results showed that the frequency of the sound increased over time and that the speed of sound aligned with theoretical values at room temperature. The researchers also conducted experiments with hot air to observe any differences in the frequency response. Overall, this experiment provides a simple and replicable way to determine the speed of sound in air, making it a valuable teaching tool for acoustics. [Extracted from the article]

One student (say A) holds a smartphone (with its accelerometer measurement function on) away from the other participant (say B), whose reaction time is being measured (see Fig. To measure the reaction time, one needs to find the time interval in which the accelerometer displays the acceleration value close to the value of I g i (or zero if you are using it in "acceleration without I g i " mode). [Extracted from the article]

We consider a cylindrical metallic magnet that is set into rotation about a horizontal axis by a falling mass. In such a system the magnetic field causes a radial current which is non-solenoidal. The current leads to charge accumulation and a partial attenuation of the radial current. The magnetic field acting on the radially flowing current slows down the acceleration. We evaluate the angular velocity and displacement using Newtonian dynamics. We show that the electromagnetic angular momentum must be taken into account to calculate the change in the angular momentum due to the external torque on the system. The loss in the potential energy of the falling mass can be explained only by taking into consideration the electrostatic energy and the Joule loss. [ABSTRACT FROM AUTHOR]

The article focuses on the pedagogical concept of Doppler effect connecting to sources with constant accelerations for high school students. Topics discussed include explanation of the theory of Yukawa, description of effect for sound waves and one-dimensional kinematic model for Doppler effect. It presents information of mechanical model based on formulas of the effect.