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Baseball and Altitude

(Click the Play Ball button in the lower left corner if the baseball isn't already on the screen.)

We now want to examine how the altitude at which a baseball is thrown changes our results. Note that we have three locations to choose from. Set up these conditions:

Altitude: 700 feet (Cleveland)
Speed: 100 mph
Spin: 0 (Fastball)

Click Speed at Surface on the Plotter Control Panel.

You should remember that the yellow line and the green line in the Plotter View overlap since the air accelerates around both sides of the ball at the same rate.

Now we are ready to see what happens if we go to a higher altitude where the air is less dense. Click on Denver, which is one mile high. Did you notice that there was no change in the graph and the SIDE FORCE remains zero?

Let's try to do the same thing except view the effects of altitude on pressure. Click back on Cleveland and choose Surface Pressure on the Plotter Control Panel. What happens when you click onto Denver? Are there any changes?

Note the values for the minimum of the pressure curve. The net result is that the pressure at the minimum drops as the altitude increases. Since the air becomes less dense as altitude is increased, there is less air to create the side force on the ball. Pressure is not only a function of how fast the air is moving, but is also a function of the amount of air that can create the force. Less air means less pressure.

Since the Side Force depends on the difference in pressures, we could expect a change in Side Force with Altitude.

Verify this last idea by setting a Screwball and then clicking back and forth between the sites and watching the Side Force horizontal bar change in value. The higher the altitude, the less dense the air, the lower the pressure, and the lower the Side Force.

Finally, choose Ballpark on the Plotter Control Panel and examine the effect of your pitch trajectory as you click back and forth between locations. You can also see the effect at other locations by moving the altitude slider on the Baseball Input Panel. Move the slider and release the mouse button to see the effect.

To check your results click on Mt. Everest and note what happens to the trajectory of the ball.

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