Bernoulli's Principle at Work!

Purpose: The purpose of this activity is to learn how the air pressure phenomenon works.

Materials

• thread spool
• cardboard, 7 cm by 7 cm, lightweight but firm
• pin
• science journal

Procedure

1. Cut a piece of cardboard (from the back of a notebook) so that it measures 7 cm by 7 cm.
2. Stick a pin through the center of the cardboard.
3. Place the spool over the pin so that the pin goes into the hole in the spool.
4. Hold the cardboard against the spool vertically. Blow firmly through the hole in the top of the spool and observe what happens to the cardboard.
5. Release your hand from underneath the cardboard.
6. Record your observations in the science journal.

Conclusion

• Explain why the cardboard did not fall once you removed your hand.

What's Happening?
As you blow through the top of the spool, a jet of air moves horizontally from the hole at the bottom of the spool and spreads out over the surface of the cardboard. As the air moves rapidly out of the bottom, it lowers the pressure between the cardboard and the spool. The higher pressure from the surrounding air pushes up against the bottom of the cardboard and demonstrates how the lift (pressure force) overcomes the weight (gravity) of the cardboard.

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Answer Key

1. Explain why the cardboard did not fall once you removed your hand.

As you blow through the top of the spool, a jet of air moves horizontally from the hole at the bottom of the spool, spreads out over the surface of the cardboard, and lowers the pressure between the cardboard and the spool. The higher pressure from the surrounding air pushes up against the bottom of the cardboard and "lifts" the cardboard.