Viscosity Measurement of Liquids Using the Falling Ball Method

Abstract

Viscosity is a fundamental fluid property that describes a fluid's internal resistance to flow. It is determined by molecular interactions and structural characteristics. The goal of this study was to determine and compare the viscosity of several liquids—distilled water, cooking oil, dishwashing liquid (Sunlight), and alcohol—using the falling ball method. Measurements were conducted with a Hoppler viscometer at room temperature. The density of the marbles and liquids was recalculated using the accurate volume formula (V = 4/3πr³) and pycnometer mass data. Viscosity (η) was obtained using the formula. The results showed that Sunlight had the highest viscosity (7.6 × 10⁻² Pa·s), followed by cooking oil (7.2 × 10⁻³ Pa·s), water (3.0 × 10⁻³ Pa·s), and alcohol (3.1 × 10⁻⁴ Pa·s). These results demonstrate that stronger intermolecular forces lead to higher viscosity. Errors in earlier data were due to density and timing inaccuracies (e.g., incorrect units or negative results). Overall, viscosity decreases with temperature and depends strongly on molecular size and intermolecular attraction. Understanding viscosity is essential for applications in transport processes, chemical engineering, and material design.