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Bernoulli's Principle - The Amazing Ping-Pong Ball (Amy Murphy)

Amy Murphy

Principles Illustrated

Bernoulli's Principle

Standards

8th Grade Physical Science

Forces

  1. Unbalanced forces cause changes in velocity. As a basis for understanding this concept:
    1. Students know a force has both direction and magnitude.
    2. Students know when an object is subject to two or more forces at once, the result is the cumulative effect of all the forces.
    3. Students know when the forces on an object are balanced, the motion of the object does not change.
    4. Students know how to identify separately the two or more forces that are acting on a single static object, including gravity, elastic forces due to tension or compression in matter, and friction.
    5. Students know that when the forces on an object are unbalanced, the object will change its velocity (that is, it will speed up, slow down, or change direction).
    6. Students know the greater the mass of an object, the more force is needed to achieve the same rate of change in motion.
    7. Students know the role of gravity in forming and maintaining the shapes of planets, stars, and the solar system.

Questioning Script

Prior knowledge & experience:

How can you move the ping pong ball from one cup to the other without touching the cups or the ball? 

Root question:

How did you get the ping pong ball to move?

What caused the ball to move?

Target response:

you can move the ball from cup to cup by blowing into the cup at a slight angle.  The ball moves because of Bernoulli's principle.  The faster a fluid moves over a surface, the less pressure it exerts.  So when you blow into the cup, the air moves faster and then the pressure pushing down on the ping pong ball decreases and the ping pong ball will rise out of the cup where it can then be blown into the next cup.

Common Misconceptions:

When you blow on something it will push down or move away from the force.

Photographs and Movies

PicasaWeb Slideshow


References

Wikipedia: Bernoulli's Principle

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