MATERIALS:

Clear rubber tubing (2-3 feet, 1 in. diameter works best.), 2 raw eggs (doesn't hurt to have some extra on hand), 2 plastic garbage bags with holes for arms and head, paper towel for clean up.

OBJECTIVE:

Egg Blow can be used as a fun activity involving air flow, pressure and force. Two students compete trying to blow egg yoke through the tube onto the other student. You can clue one of the students in by having them create a seal on their end of the tube with their lips. This creates a sealed container and no matter how hard the other student blows the egg yoke will not move. By using this activity and some questioning your class can discover the laws for air flow.

PROCEDURE:

Round one:

Raw egg yoke is placed in the center of the clear rubber tube. Two volunteers are called up to participate in the egg blow competition (take either volunteers or students that you feel will be good sports.) The volunteers should put on the garbage bags to protect their clothing. Have the two volunteers take opposite ends of the tube. They should hold the tube carefully in their hand so the egg yoke does not slide out of the tube. The two volunteers hold the tube to their mouth and the instructor says "Go". In the first round let the students compete normally by blowing and see who wins. Question the students about what just happened (see Questioning #1 below.)

Round two:

Without telling the winner have the other volunteer create a seal at their end of the tube using their lips so no air escapes. Make sure you tell the person who is sealing the tube not to blow. Let the two students compete again, same procedure as the first. When the student who is blowing hard, trying to win his/her second straight competition stops to take a breath of air. Have the student that was sealing their end of the tube blow the egg out of the tube. Hopefully making for a good laugh.

Thank your volunteers and have the student who sealed the tube describe what they did.

QUESTIONS:

1. Have the students describe what happened in the first round of Egg Blow in terms of force and pressure. Why did the egg come out of the end it did?

2. Have the students describe what happened in the second round of Egg Blow in terms of force, pressure, and air flow. Why didn't the same thing that happened in round one happen in round two?

EXPLANATION:

In the first round of Egg Blow the egg yoke goes to the end of the tube of lesser force. In the second round when one end of the tube is sealed the reason for the egg yoke not moving is air flow in equals air flow out. Since no air flow is able to move out of the tube, the air being blown at the opposite end of the tube is not able to apply a force to the egg yoke. Because there is no air flow out, no matter how hard you blow it has no effect on the egg yoke.