PART 2: Rotational Inertia of the Ring

Before we do our measurements, it would be smart to make an estimate of what we should expect. Theoretically, the rotational inertia of a thick ring

is given by with the mass of the ring, the outer radius, and the inner radius.

QUESTION 12: Measure the dimensions of the ring. Outer radius: 38 mm Inner radius: 27 mm QUESTION 13: Use a scale to measure the mass of the ring. Mass of the ring: 490 grams

QUESTION 14: Calculate the theoretical value of using the

measurements of the mass and the diameters. Expected rotational inertia of the ring: QUESTION 15: Now place the ring on top of the disk such that the

tiny pins lock into the disk. Follow the steps in the procedure section

and ﬁll in Table 2 below. Do four runs, each with a different mass

added to the hanger as indicated. Additimnll mass Total mass Angular acceleration Calculated ml: ' ' lg] ol" hanger lg] [rnds'ﬂ inertia [kg c1113]

None TYPE ANSWER 2 Run #1 (just the hanger) HERE 1.31 rad/s TYPE ANSWER HERE Run #2 5 gram TYPE ANSWER 2.48 rad/s2 TYPE ANSWER HERE

HERE Run #3 10 gram TYPE ANSWER 4. l 3 rad/52 TYPE ANSWER HERE

HERE Run #4 15 gram WP%%§:WER 5.40 rad/s3 TYPE ANSWER HERE Table 2: Measurements of the angular acceleration, and the calculated

total rotational inertia. QUESTION 16: Use the rightmost column of Table 2 to calculate the

average . Average rotational inertia of the ring+disk+wheel together: