Hendra J. Smart Free-Fall Experiment Apparatus Using Arduino, Infrared–Ultrasonic Sensors, and Bluetooth Data Logging. Edusainstika: Jurnal Pembelajaran MIPA [Internet]. 2025Dec.31 [cited 2026Jan.20];5(2):70-8. Available from: https://ejournal.uinmybatusangkar.ac.id/ojs/index.php/Edusainstika/article/view/16256