Funnel Fun

Purpose: The purpose of this activity is to apply Bernoulli's Principle to understand why birds, kites, and planes can fly.

Materials

• 1 clean funnel with a narrow opening of 1 cm or less
• 1 table tennis ball
• science journal

Procedure

1. Bend your head back so that you will be able to blow the table tennis ball toward the ceiling.
2. Put the ball in the top of the funnel and blow hard and fast into the stem of the funnel.
3. Record in your science journal what happened to the ball.
4. Bend your head down so that you will be able to blow through the funnel straight down toward the floor.
5. Hold the ball inside the funnel close to the hole (temporarily) and take a deep breath.
6. Let go of the ball as you blow hard through the stem of the funnel until you use all air in your lungs.
7. Record in your science journal what happened to the table tennis ball.

What's Happening?
Bernoulli's Principle states that when the speed of a moving fluid (air) increases, the pressure on its edges decreases. The ball clings to the funnel when it is pointed toward the ceiling when the air is blown hard and fast through the stem of the funnel. Still air exerts more pressure around the ball than that around a stream of moving air. The ball clings to the funnel when it is pointed toward the floor because the air moves away from it faster, creating a low-pressure area in the center.

Extension
Fill a cardboard box with shipping popcorn (polystyrene particles). Get a vacuum hose and place one end in the box containing the shipping popcorn. Spin the opposite end of the vacuum hose in a circular motion. As you increase the speed of the end of the vacuum hose, the air pressure will drop, and pieces of shipping popcorn will come out. The vacuum hose appears to be sucking up the shipping popcorn. That is Bernoulli's Principle at work!