MATERIALS:

1. Center tube from paper towel roll

2. 5 feet of surgical rubber tubing or "bungee" cord

3. 3 feet of cloth ribbon (do not use slippery ribbon)

4. 2 feet of bell or iron wire

5. C-clamp

6. Pliers

PROCEDURE:

1. Fold over about 1 inch of the rubber tubing and wrap it tight with a piece wire. Twist the wire tight with the pliers and as doing so, form a loop about 1 inch in the diameter in the wire.

2. Attach one end of the ribbon to the other end of the rubber tubing with a piece of wire. Twist the wire tight.

3. Slip the wire loop over the screw shaft of the C-clamp. tighten the clamp to the end of a table.

4. Lay the tube and ribbon across the table. Place the paper tube on top of the ribbon at its free end and roll it up snugly in the ribbon.

5. While keeping the ribbon from slipping, pull the paper tube back to stretch the rubber tubing. Release the tube. The tube will be spun as the rubber tubing spins it at the same time. With enough speed and spin, the paper tube will lift off the table and may fly a loop through the air.

QUESTIONS:

1. In what direction was the tube spinning?

2. How is the air moving around the tube as it flies through the air?

3. What effect does the movement of the air have on the tube?

4. How could you make the tube turn right, left, or down?

RATIONALE:

We all know that a baseball pitcher can throw a ball in such a way that it will curve off to one side of its trajectory. This is accomplished by imparting a large spin to the ball. The same is true for the tube. The thin layer of air is dragged around the spinning tube by friction. The spinning air gives a greater velocity to the air on one side of the tube creating lesser pressure on that side of the tube. Since the air pressure is then greater on one side of the tube than the other, the tube curves. This is another application of Bernoulli's principle.

APPLICATIONS:

Curving baseballs and tennis balls