The Humble Rubber BandThe Humble Rubber Band

is your Friendis 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 AttackersYou 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