Purpose: To measure the rotational inertia (moment of inertia) of a physical pendulum and compare it with the calculated value.

Option 1: A meter stick mounted to pivot about one end, a stop watch or timer.

Option 2: A meter stick mounted to a Rotory Motion Sensor attached to the Pasco 750 interface.

Set the meter stick into small oscillations and measure the time for several (e.g., 5) oscillations. Divide by the number of oscillations to get the period. Starting with the equation for the period of a physical pendulum, solve for the rotational inertia. Then, use the measured period to calculate the rotational inertia in terms of the mass of the pendulum. (The distance from the pivot to the center of mass is, of course, 0.5 m.) The rotational inertia of a rod suspended from one end calculates to (1/3)ML2 (for the usual symbols). For a meter stick, this is (1/3)M in appropriate SI units. The experimental measurement described above should give an answer very close to this value.

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