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Bernoulli's Law

The pressure of a moving fluid such as air is less when the fluid is moving faster.

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What a Drag!

What a Drag!

Credit: jayhem
Source: http://www.flickr.com/photos/jayhem/3601351382/

When you’re swimming, the buoyant force of the water helps overcome the downward pull of gravity. As a result, you feel much lighter. But the water creates another problem for the swimmer. It’s called drag.

Why It Matters

• Drag is a swimmer’s biggest enemy. Water is 700 times as dense as air, so it’s a lot harder to move your body through it. If you’ve ever tried to run through shallow water at a beach or pool, then you’ve experienced drag.
• To be a champion swimmer, you need to know how to overcome drag.
• Credit: Jim Bahn
Source: https://www.flickr.com/photos/gcwest/136945653

In order to swim against the drag, the swimmer cups her hands, creating thrust [Figure2]

• What exactly is drag, and how can a swimmer overcome it? Watch this video to find out: http://www.nbclearn.com/summerolympics/cuecard/59572

Show What You Know

1. Two key forces involved in swimming are thrust and drag. Define these two forces.
2. Three types of drag work against a swimmer. Identify and describe the three types.
3. How can a swimmer reduce drag?
4. How does a swimmer create thrust?
5. A swimmer can use her hands and arms to create lift, like the lift created by an airplane wing. In the case of a swimmer, however, the lift is created in a forward rather than upward direction. What technique allows the swimmer to create lift? How does this technique work?

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Color Highlighted Text Notes

1. [1]^ Credit: jayhem; Source: http://www.flickr.com/photos/jayhem/3601351382/; License: CC BY-NC 3.0
2. [2]^ Credit: Jim Bahn; Source: https://www.flickr.com/photos/gcwest/136945653; License: CC BY-NC 3.0

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