Implementation of Video-Based Laboratory Using Tracker Software

Study Case Implementation of Video-Based Laboratory Using Tracker Software to Determine Gravitational Acceleration in Various Cities in the United States and Turkey Michael Kurniawan (2018123456) University of Cincinnati, 2600 Clifton Ave, Cincinnati, OH 45221, United States kurniaml@mail.uc.edu Abstract Free fall experiments were conducted in several cities in the United States and one city in Turkey to determine the value of gravitational acceleration. Measurements were made using the Video-Based Laboratory (VBL) method. The data collected consisted of free fall motion video recordings that were analyzed using Tracker software. The analysis results showed that the values of gravitational acceleration in New York, Houston, Denver, and Istanbul were 9.793 m/s², 9.778 m/s², 9.720 m/s², and 9.760 m/s², respectively. The Root Mean Square Deviation (RMSD) values obtained were 3.849 × 10⁻² (New York), 6.598 × 10⁻³ (Houston), 2.4 × 10⁻⁴ (Denver), and 2.67 × 10⁻² (Istanbul), respectively. The measurement error rate was in the order of 10⁻², so the results were considered valid. The gravitational acceleration value obtained was close to the literature value, which is 9.8 m/s². Thus, the application of the Video-Based Laboratory method using Tracker software proved to be efficient and effective in determining gravitational acceleration in various regions of the world. Keywords: free fall motion, Tracker, Video-Based Laboratory INTRODUCTION In Physics education, scientific truth can be supported both theoretically (based on laws or principles) and empirically (based on observation results). One of the concepts in physics that is often considered constant without empirical proof is the acceleration due to gravity. Many students assume that this value is fixed because it is listed as a standard value in textbooks (Subhan et al., 2022). According to Tipler (2008), the MICHAEL KURNIAWAN 1 Study Case acceleration due to gravity at the Earth's surface is 9.81 m/s². However, research by Torres-Payoma et al. (2022) shows that the Earth is not a perfect sphere but a rotating ellipsoid, so the acceleration due to gravity can vary between locations due to differences in altitude and the distribution of the Earth's mass. Gravitational acceleration can be determined through simple experiments relevant to the high school level, such as simple swings, dynamic trains, parabolic motion, and free fall motion (Elot et al., 2022). Of these methods, free fall motion is the most practical experiment because it requires little equipment and can be conducted outside the laboratory. However, direct observation often yields limited data. Fatimah et al. (2020) stated that many students have difficulty determining the initial velocity, instantaneous velocity, and acceleration of objects in the phenomenon of free fall. These values can be calculated using the following equations: 1 𝑦 = 𝑔𝑡 2 (1) 2 𝑣 = 𝑔𝑡(2) These quantities are difficult to measure accurately with conventional tools such as rulers or stopwatches. Therefore, digital devices are needed to obtain more precise data. With advances in technology, free fall motion analysis can now be performed using the Video-Based Laboratory (VBL) method. Rodriguez et al. (2000) define VBL as a computer laboratory that enables the analysis of physical phenomena from video recordings, including stroboscopic images. Through pixel-based analysis, this method allows the observation of phenomena that are too fast for the human eye to see. This study uses Tracker software, a free application for video analysis and modeling designed specifically for physics education. Various previous studies have utilized Tracker to observe physical phenomena that are difficult to observe directly. For example, Rismaningsih et al. (2022) studied the moment of inertia of composite objects through rolling motion, Handayani et al. (2022) assessed the effectiveness of Tracker in gravity acceleration experiments, and Zaidi (2022) used Tracker to analyze ball throwing motion. Based on these studies, the Video-Based Laboratory method using Tracker is believed to be applicable for determining gravitational acceleration in various parts of the world. This study was conducted in several cities in the United States (New York, Houston, and Denver) and one city in Turkey (Istanbul). The research question is: Is the MICHAEL KURNIAWAN 2 Study Case application of the Video-Based Laboratory method using Tracker software effective and efficient in determining gravitational acceleration in various locations around the world? The objective of this research is to determine the acceleration due to gravity in several cities by implementing the Video-Based Laboratory analysis method using Tracker software. METHODS 2.1 Research Design This study used a free-fall motion experiment method analyzed with Tracker software based on Video-Based Laboratory. 2.2 Research Sample The data used were free-fall motion video recordings. The recordings were taken in three cities in the United States (New York, Houston, and Denver) and one city in Turkey (Istanbul). The researcher did not directly record the footage, but delegated the task to fellow researchers following the same standard procedures at each location. 2.3 Research Techniques The equipment used included balls (rubber balls, baseballs, and ping pong balls), rulers or measuring tapes, tripods, and smartphone cameras. Table 1. Types of balls and length markers used The ball served as the object of analysis to determine its movement characteristics. The length marker was used to calibrate the pixel length against the actual distance. MICHAEL KURNIAWAN 3 Study Case Figure 1. Free fall motion experiment device. The recording procedure was carried out by ensuring that the video background contrasted with the color of the ball, placing a long marker in the shooting area (using a ruler or tape measure), then dropping the ball from a certain height while recording using a smartphone mounted on a tripod. The video data was then analyzed on a laptop using Tracker. In Tracker, the analysis was performed using the Track feature. The initial steps included setting the coordinates to determine the position of the ball in each frame, setting the Calibration Stick according to the length marker, and selecting the start and end frames to facilitate analysis. After this process, the Track feature was used to generate tables and graphs as shown in the following figure. Figure 2. Video analysis using Tracker. MICHAEL KURNIAWAN 4 Study Case To determine the acceleration due to gravity, the Analyze feature in the Data Tool tab is used, selecting a parabolic curve fitter for the position versus time (y-t) graph and a linear fit for the velocity versus time (v-t) graph, as shown in the following figure. The equation used for curve fitting is: 𝑦 = 𝐴𝑡 2 + 𝐵𝑡 + 𝐶 This equation is identical to the free fall motion equation: 1 𝑦 = 𝑔𝑡 2 2 Thus: 1 𝐴 = 𝑔 ⇒ 𝑔 = 2𝐴 2 The rms deviation value or measurement error is considered reasonable if it is within the range of 1% or of the order of 10⁻². Figure 3. Data Tool tab display containing the results of the Track feature RESULTS AND DISCUSSION Based on the results of analysis using Tracker software, data on gravitational acceleration was obtained in several sample cities, namely New York, Houston, Denver, and Istanbul, as shown in the following table: MICHAEL KURNIAWAN 5 Study Case Table 2. Results of free fall motion analysis using Tracker From the table, it can be seen that the gravitational acceleration values in each city are 9.793 m/s² (New York), 9.778 m/s² (Houston), 9.74 m/s² (Denver), and 9.76 m/s² (Istanbul). The Root Mean Square Deviation (RMSD) values produced are 3.849 × 10⁻², 6.598 × 10⁻³, 2.67 × 10⁻², and 2.20 × 10⁻⁴, respectively. The measurement error is in the order of 10⁻², so the results are scientifically acceptable. Measurement errors can originate from parallax effects during length calibration due to the camera position not being completely perpendicular to the vertical plane (angle ≠ 0° or 90°), as well as inconsistencies in manual tracking of the object's center of mass (manual track) or failure of the autotrack feature when the ball color is not detected consistently in each frame. In general, the gravitational acceleration values obtained are close to the literature values (9.8 m/s²) and show a downward trend at higher elevations. This is consistent with the theory that gravitational acceleration is inversely proportional to the square of the distance from the center of mass of the earth. However, it should be noted that local gravity values are not only influenced by altitude, but also by other factors such as: • Average elevation above sea level. • The shape of the geoid (the Earth's equipotential surface), where the gravitational force acts perpendicularly at each point (Payoma et al., 2022). • Geological composition (lithology) in the data collection area. • Centrifugal acceleration due to the Earth's rotation. These factors are not the focus of this study because the research focuses more on the efficiency and effectiveness of implementing the Video-Based Laboratory (VBL) method using Tracker software to determine gravitational acceleration. MICHAEL KURNIAWAN 6 Study Case Based on the analysis results, the implementation of VBL using Tracker proved to be: • Effective, because the gravitational acceleration values obtained were very close to the literature values. • Efficient, because the equipment used was simple and data collection could be carried out without the researcher being present at the location. In addition, various previous studies have also shown the effectiveness of Tracker in enhancing the learning experience of students, especially in validating physical values that are difficult to observe directly. Sari et al. (2019) emphasized that creating interesting and technology-based physics learning at the secondary level is an important mission that can be supported by the use of devices such as Tracker. Thus, this method not only facilitates the accurate determination of gravitational acceleration, but also serves as an interesting and applicable learning tool for students and novice researchers. CONCLUSION The Tracker software has been proven capable of analyzing motion that is difficult to observe directly with the human eye at a low cost and with a simple analysis process. Although it is an alternative method, the gravitational acceleration measurements obtained are close to the literature values, namely 9.793 m/s² (New York), 9.778 m/s² (Houston), 9.74 m/s² (Denver), and 9.76 m/s² (Istanbul), with Root Mean Square Deviations of 3.849 × 10⁻², 6.598 × 10⁻³, 2.67 × 10⁻², and 2.20 × 10⁻⁴, respectively. Measurement errors in the order of 10⁻² indicate a level of accuracy that is scientifically acceptable. Therefore, the implementation of the Video-Based Laboratory (VBL) method using Tracker software to determine gravitational acceleration in various regions of the world is considered efficient and effective. As a recommendation, further research should use a high-resolution camera with a speed of 60 frames per second to obtain more precise data. The failure of the autotracking system in Tracker is often caused by inadequate video quality, so improving the camera specifications will have a significant effect on the accuracy of the analysis results. MICHAEL KURNIAWAN 7 Study Case REFERENCE MICHAEL KURNIAWAN 8