Willie’s Knee - Wednesday, July 26, 2006

Willy slipped off the deck onto the lawn and broke his knee. How could that be? The lawn is soft, why should his knee break?

Here's why.

While the lawn is made of soft grass, the grass grows in the hard unyielding earth. Willie weighs 170 pounds if he weighs an ounce, so 170 pounds of Willie met the hard unyielding earth.

Try this thought experiment:

Imagine that you are lying on your back, legs flat, on the lawn, on the hard unyielding earth. Now imagine bringing one foot towards you so that your leg forms a triangle with the earth; your knee is raised above the level of your head.

Now let me drop a 170 pound anvil onto your knee from a height of three feet.

You don't like?

Of course not, but how different is that from Willie's mass dropping his knee onto the hard unyielding earth?

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