Gravity-driven fluid oscillations in a drinking straw

10.1119/1.5095945.1We describe a simple experiment observing oscillations of fluid in a drinking straw immersed in a bath of water. The motion of this oscillator system with changing mass is matched remarkably well by a model derived from Newton's laws with the inclusion of only a phenomenological damping coefficient. We compare the frequency of the oscillations to Hooke's law for small displacements and find 0.25% discrepancy. This experiment can be shown as a demonstration of oscillations of fluids, or it can be performed by students as a laboratory activity in upper-division undergraduate physics and engineering courses.10.1119/1.5095945.1We describe a simple experiment observing oscillations of fluid in a drinking straw immersed in a bath of water. The motion of this oscillator system with changing mass is matched remarkably well by a model derived from Newton's laws with the inclusion of only a phenomenological damping coefficient. We compare the frequency of the oscillations to Hooke's law for small displacements and find 0.25% discrepancy. This experiment can be shown as a demonstration of oscillations of fluids, or it can be performed by students as a laboratory activity in upper-division undergraduate physics and engineering courses.