The Humble Rubber Band is your Friend  to warm yourself when you are cold.  to cool yourself when you are hot.  to ward off dangerous attackers.  to protect yourself from lethal ozone levels.  to insulate yourself from increasing gasoline prices.  to hold things together. It will help you: How does it do all of these wonderful things?

The Hysteresis Loop

Properties of the Rubber Band  It takes more energy to stretch than you get back when you let go.  The energy inside the hysteresis loop is converted to heat.  Both the top curve and the bottom curve can be accurately modelled using a cubic function.  Rubber is made up of long chains of molecules.  When the rubber band is at rest, the molecules are tangled, and entropy is high.  When the rubber band is stretched, the molecules straighten somewhat, and entropy is decreased.  When the rubber band is released, the molecules tangle again, and entropy is increased.  When entropy is lowered, the band gives out heat.  When entropy is increased, the rubber band takes in heat.

The Negative Coefficient of Expansion  If you heat the rubber band, it will contract.  If you cool the rubber band, it will expand.  You can demonstrate these effects using a rubber band, a weight, and a heat gun.

From Theory to Practice  If your lip is cold, stretch the rubber band, and apply it to your lip.  If your lip is hot, stretch the rubber band, wave it around in the air, let it contract, and apply it to your lip.

Warding Off Attackers  You can use your fingers and the rubber band to make a “gun” to shoot dangerous attackers. However, you may find that the band does not travel very far due to air resistance.  To stabilize the flight of the band, you must impart a “spin” to it when firing.  Hold your hands such that the tops face each other, and your index fingers point down. Suspend the band between your index fingers.  Twist your hands around such that your index fingers point up. In doing so, you will twist the band such that one side is under more tension than the other.  When you fire the band, it will spin, similar to a frisbee with a hollow centre.  This will add stability to the flight, decreasing air resistance, and greatly increasing the range and accuracy.  Fun Fact: if you could get rid of air resistance entirely, you could shoot the band over a kilometer.

Lethal Levels of Ozone  Ozone will quickly oxidize a rubber band.  Oxidation makes the band brittle, and it breaks under tension.  Suspend a weight or bucket of water from the ceiling using a rubber band.  If high levels of ozone should occur, the band will break, alerting you to the danger.

Beat the High Cost of Gasoline  Combine the energy you can store in a rubber band with Newton’s Third Law of Motion.  Construct the apparatus shown, and attach it to the top of your car.  When you wish to travel, cut the string.

The End  Built by John Bain of Wilmington, Delaware.  Contains 850,000 rubber bands.  Height: 1.5 m.  Mass: 1418 kg. World’s Largest Rubber Band Ball