Barometer Simulation
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This app is designed to help students connect atmospheric pressure, liquid density, and gravity in one visual model. Instead of memorizing formulas, students can drag a probe, change planets, switch liquids, and see how the barometer column responds.
What This Simulation Demonstrates
The core idea is hydrostatic balance in a barometer:
$$P_{atm} = \rho gh$$
- where $h$ is the height of the liquid column.
- Lower density liquids require a taller column for the same atmospheric pressure.
- Higher atmospheric pressure produces a taller column for the same liquid.
- Different planets change both gravity and baseline atmospheric pressure, which can dramatically change column height.
- The top of the barometer tube is modeled as vacuum, so pressure there is approximately zero.
- Inside the column, pressure increases with depth.
How To Use It In Class
- Start with Earth and Mercury to establish the classical barometer case.
- Ask students to predict what happens when switching from Mercury to Water or Ethanol before changing settings.
- Use the altitude slider and ask why column height decreases as altitude increases.
- Switch planets and ask students to decide whether pressure or gravity is the stronger effect in each case.
- Drag the probe to compare pressure in vacuum, in the liquid column, and in the reservoir.
Tip: Keep one variable fixed while changing another (for example, keep planet fixed while switching liquid) so students can isolate cause and effect.