Under Pressure

by Will Boyd

wbDid you know that your shoulders support 14.7 lbs per square inch of the earth’s atmosphere? That’s right! You are carrying a burden even when your backpack is in the closet. It rises from your shoulders and extends to the edge of the atmosphere 80 km above sea level.

This semester a team of intrepid budding scientists and I have been delving into the physical science of the magnificent sphere the good Lord has given us to care for and call home. We have been measuring our desks in cubits, peeling back the layers of science involved in the climate change debate, and most recently building our own aneroid and water barometers.

Barometers measure air pressure. Rather than air pressure only weighing us down through the force of gravity, air pressure pushes on you and me and all things on the earth in all directions equally. Thanks to this phenomenon it is fairly easy to build an aneroid thermometer. The air trapped under the latex balloon in the homemade barometer above will expand and contract proportionally to the air pressure in the room. The balloon expands and the pressure gauge (drinking straw with quilting pin glued to the end) drops. The balloon contracts and the pressure gauge goes up. So far this week the air pressure here has fluctuated by about 6 mm according to my aneroid barometer.

The water barometer functions under the same principle but uses water displacement to show changes in air pressure.

I love the barometer project because it gets students thinking about the tools of science and puts them in the driver’s seat where they collect real data without a pre-determined outcome. I wonder if we can measure air pressure in cubits?

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