Development of a Low-cost Apparatus for Free Fall Experiment using a Microcontroller

  • Tan Kingkunya Ubon Ratchathani University
  • Amorn Thedsakhulwong Ubon Ratchathani University
  • Udom Tipparach Ubon Ratchathani University
Keywords: microcontroller, Arduino Nano, free fall apparatus, gravitational acceleration


The authors have developed a low-cost apparatus for a free fall experiment using a microcontroller to measure an acceleration due to gravity of the earth. The developed apparatus can be controlled and collects data by using the Arduino Nano microcontroller board with ATmega328 and IR-Sensor switch E18-D80NK. The relation of position and time of the falling object was obtained by letting stainless steel spheres fall. The experiments were tested with three different balls with mass of steel balls 33.0 grams diameter 18.0 millimeters, 66.0 grams diameter 25.2 millimeters and 45.0 grams diameter 30.5 millimeters.  Each ball was held and released by solenoid electromagnets at 15 different heights from 0.10 meters to 0.85 meters. The falling times were measured in milliseconds. The results show that the accelerations due to gravity of the earth obtained from different balls were not different. The average of the acceleration due to gravity of the earth was 9.8502 m/s2 when compared to the acceleration due to gravity of the earth calculated using standard formula at Ubon Ratchathani Province 9.7839 m/s2, the average error was 0.67 percent. These data show that the developed apparatus with a budget of 1,380 Baht yields the precise value of the acceleration due to gravity close to the value obtained from the calculation from standard formula. When compared to an expensive commercial timer (J0201-4C) with resolution 0.01 microseconds, the time from the developed experiment set has an absolute error of 1.5 ms from the J0201-4C timer.