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Estimating with air 2

Page history last edited by Joe Redish 6 years ago



In our study of pressure in fluids, we discovered that the pressure depended on depth because the fluid below is holding up the weight of all of the fluid above it. For the air, we are at the bottom and can measure the pressure (~100 kPa)* and the density (~1 kg/m3) of the air, but we don’t know how deep we are. Let’s figure it out.


  1. What is the weight of air being help up by a thin square of air just above the ground if the square has an area of 1 m2?

  2. To get an idea of how high up the atmosphere must go, assume that the air above us is approximately a uniform density, like water is. If that’s true then what is the height h of the column of air you calculated in A?**

  3. Estimate the force the air in the room in which you live pushes up on the ceiling of your room. You may approximate the density of the air in the room as a constant. Do you think this is a good approximation?


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