Phoenix Business Daily

How would I conduct a lab to find rotational inertia for a bicycle wheel?

Given: A bicycle wheel without the tire on it, string, a set of known masses, other commonly available equipment. Find: The rotational inertia of the wheel. I received this yesterday in class and have to have it finished by tomorrow but can't seem to figure out how to go about it. Everything I can think of seems too easy.

Public Comments

1. Weigh the wheel and whatever axle you will use for the experiment seperately. Attach wheel to axle (Pick a nice symmetrical cylinder for this, lol). Wind the string around the axle and run it over to a pulley so that the weight can fall without interfering with the wheel if it's horizontally oriented. If you mount it vertically then you don't need the pulley. Let the weight go from a known height but make sure it hits the floor before you run out of string and measure the max speed of the wheel (Ideally the speed it is spinning when the weight hits the floor). From there you know what the potential energy of the weight was, that was all put into the rotational inertia of the wheel AND the axle. Find the total rotational inertia of the system, then subtract out your known rotational inertia of the axle. There ya go!