Rolls in Sync

PREDICTION CHALLENGE: ROLLS IN SYNC!

GIVEN: Two rolls of toilet paper and a meterstick

TASK: Determine the ratio of heights so that both

rolls land at the same time when dropped as shown

on the picture.

POSTER: Force diagrams and a complete derivation

of ratio of the two heights

DATA:

R: outer radius

r: inner radius

Rotational inertia for a cylinder:

Rotational inertia for unrolled roll rotating about its outer radius:

(Thanks to Dolores Gende for this activity)