May 25th, 2010

Colin McGuire and Catherine Hendricks, BigSURS 2011

Measuring Viscosity with a Driven Damped Harmonic Oscillator
Presented at the 2011 Big South Undergraduate Research Symposium (BigSURS)

A typical problem solved in a junior/senior level classical mechanics course is the driven, damped harmonic oscillator with a linear drag force. This experiment is surprisingly difficult to build because the linear drag is dependent on the diameter of the oscillator along with other parameters, yet the experiment can be used to measure the viscosity of the medium if designed correctly. In this experiment a vertical driven, damped harmonic oscillator was used to measure the viscosity of water, ethylene glycol (EG), and 8, 5, and 3 percent by weight concentration of poly-ethylene glycol (PEG). Water and ethylene glycol were used as controls. Data was analyzed using a Lorentz curve fit to calculate values for gamma, a variable used to calculate the viscosity of the fluid. The viscosity of the polymers decreased with a decrease in concentration. The experimental design and experimental results will be presented.