Half wood and half metal physical pendulum with suspension points at both ends.

### What it shows:

The period of a physical pendulum is measured and compared to theory:

where I is the rotational inertia, g is the acceleration due to gravity, and x is the distance from the pivot to the center-of-mass. For a uniform rod, the center-of-mass is literally at the center of the rod. In this demonstration the physical pendulum is half steel and half wood so that the center-of-mass location is non-trivial, but can be found by balancing the pendulum. The moment of inertia about each pivot can then be determined from

### How it works:

The physical pendulum is a 2 cm square by 92 cm long "rod," half of which is steel and the other half wood. Small holes positioned 1.5 cm from each end serve as suspension pivot points.

A digital wristwatch or large analog timer ^{1} is used to measure the period when the pendulum is swung from each of the two pivots.

### Setting it up:

Use standard lab clamps and rods mounted on the lecture bench.

1 Sargent-Welch Scientific model 812