MechanikZ

This free, ad-free and data protection compliant app was specially developed for physics lessons. Experiment instructions and a version for older devices can be found at https://spaichinger-schallpegelmesser.de. Physical knowledge of reference systems is required for correct operation and evaluation of the data. To start a measurement, please tap on "Start" and then either on "Measurement with gravitation" or "Measurement (inclined plane)". If the measurement does not start then, the accelerometer has been deactivated on your device. This can usually be remedied by first shutting down the device and then restarting it after approx. 5 minutes. This app uses the 3D acceleration sensor to determine the acceleration vector. The vector arrow is displayed together with the force vector arrow in real time in a 3D coordinate system. In addition, the app calculates the speed and position vector through integration. The measured values ​​of the components of these vectors are shown in diagrams together with the acceleration values, the impulse values ​​and the force values. If the smartphone or tablet has a 3D gyro sensor, the angular speeds are also recorded using the 3D gyro sensor and also displayed as graphs. A functional fit is integrated into the app to evaluate all measured values. Here, polynomials from 0 to 4 degrees and sine functions can be selected as function terms. Optionally, an optimization for harmonic oscillations can be switched on before or after the measurement. In this optimization, the initial values ​​for vx (t) and sx (t), vy (t) and sy (t) or vz (t) and sz (t) are automatically optimized for a harmonic oscillation and the low-frequency integration inaccuracies are automatically optimized High-pass filters are automatically eliminated, so that very good diagrams and sine fits are generally output. The app also has a low-pass filter that can be set or switched on and off even after the measurement. This allows high-frequency interference such as vibrations to be filtered out. In addition, after performing the function fit, the tangents to the graphs of the fit functions sx (t) and vx (t), sy (t) and vy (t) or sz (t) and vz (t) can be displayed. This is useful, for example, to work out the relationship between sx (t), vx (t) and ax (t).

In addition, the measurement results can be saved, opened, sent and received as a CSV file. An effective calibration routine that can correct for zero offset, scaling errors, and even the non-orthogonality of the accelerometer axes is also implemented. Please note that this calibration cannot correct the considerable noise of the acceleration sensor, possible temperature dependencies and hysteresis. This app enables quick measurements and simple evaluations. However, the accuracy of this app, especially the speed and position vectors, is limited by the considerable errors of the acceleration sensor. As a result of the integration or double integration, the residual error present after the calibration increases linearly or quadratically over time. This generally leads to considerable errors in the speed and location values ​​occurring after just a few seconds. In the case of experiments that are often very short-term in physics, this is usually not a problem.

If you have any questions or find errors, I would be happy to send you an email: [email protected].