Development of a Liquid Density Measurement Device Based on the Integration of Fluid Pressure and Spring Elasticity as an Alternative Physics Demonstration Tool

Abstract

Physics learning in schools requires the availability of adequate measuring instruments to enable students to conduct empirical observations and connect theoretical concepts with real-world phenomena. One of the essential instruments in fluid mechanics instruction is a device for measuring fluid density. However, limitations in laboratory facilities often result in the unavailability of such instruments, thereby reducing the effectiveness of practical learning activities. This study aims to develop a simple, low-cost, and easily replicable liquid density measurement device by integrating the principles of fluid pressure and spring elasticity as its measurement mechanism. This research employed a development methodology consisting of three main stages: (1) the design phase, which focused on determining the working principles and selecting components that could be constructed using readily accessible materials; (2) the development phase, involving the fabrication of a prototype using simple materials; and (3) the testing phase, conducted to evaluate the accuracy and consistency of the measurement results. Water was selected as the test fluid because its standard density value is widely recognized as a reference. The resulting prototype operates by converting changes in hydrostatic pressure into spring displacement, which is subsequently calibrated to obtain the corresponding density value. Experimental evaluation demonstrated that the device produced a density measurement of 0.95 g/cm³ with an error margin of 0.05 g/cm³ relative to the reference value, indicating that the instrument is sufficiently accurate for instructional purposes. Overall, this development provides a practical contribution to physics education by offering an affordable and functional alternative laboratory instrument with strong potential to enhance students’ experimental activities and deepen their understanding of fluid mechanics concepts.