This simple Swinging Rod with a variable point of suspension allows one to investigate moment of inertia and the parallel axis theorem: a really simple, elegant and insightful mechanism to explain how the time period of an oscillator changes with moment of inertia about an axis. Use it to investigate nonlinear relationships and for connecting maths to physics.
In this experiment, the object of interest is a rectangular wooden rod, specifically, a meter rule of mass M and length L. The rod can be hung on-to a pin pivoted on a firm post. To experiment with different moments of inertia, there is a series of holes drilled through the midline of the rod.
As shown in the figure, the position of the pin is P and the rod is made to swing in a vertical plane about this pivot. The center of mass is, of course, the geometric center of the wooden rod, point O. Students are required to measure the time period T of the oscillation with a stopwatch as the pivot P is varied and plot a graph between T and d = OP.
These observations are analysed for uncertainities and compared with the mathematical model.
