Angular Momentum and the Rolling Chain
- flexible loop of chain with inner diameter of 20 cm
- short wooden cylinder with outer diameter of 20 cm attached to a drill bit so it may fit into the end of an electric drill
- AC electric drill
- eye protection and gloves
Preparation and Assembly:
- Put on gloves and protective eyewear.
- Insert the wooden cylinder into the end of the electric drill and tightly lock drill bit in place.
- Fit the chain over the wooden cylinder.
- With the audience a safe distance away, hold the drill perpendicular to the ground and begin spinning the wooden cylinder.
- Some upward manipulation of the drill may be necessary in order to keep the chain from sliding off the cylinder.
The goal is to spin the cylinder and the chain up to the full revolutions per minute of the drill (which is usually about 2000 rpm for an average handheld power drill).
- Once the cylinder and the chain are at sufficient angular velocity, slightly tilt the drill towards the ground in order to let the chain slide off the cylinder.
- Once released, the chain will grip the ground and roll along in a straight line like a rigid wheel until friction brings it to rest (the speed of the released chain should be about 10 m/s).
- You may wish to repeat the deomonstration, this time placing a ramp in the chain's path that will cause it to "jump" into the air. The chain will maintain much of its circular shape during flight.
UBC Physics and Astronomy
Physics 420: 2008-2009