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### What is a general definition of bulk modulus?

If $V_f \approx V_i$, then $$\ln\left(\frac{V_f}{V_i}\right) = \ln \left( 1 + \frac{V_f - V_i}{V_i} \right) \approx \frac{V_f - V_i}{V_i}.$$So the two formulas are functionally equivalent so long as ...
• 48.4k
1 vote

### Why is the work done by an expanding ideal gas $\textbf{P}_{ext}\Delta V$?

Word done by the gas on the piston (or deformable wall) is $p_{int} \Delta V$, and work done by the piston on the outside atmosphere of pressure $p_{ext}$ is $p_{ext}\Delta V$. The difference \$(p_{int}...
• 36.9k
1 vote

### Different types of pressure and their sources

We sense (measure) pressure as a force on a unit area. Consider standing at a measurement point on a given area. The two levels to consider the force we would feel are the molecular and the bulk. At ...
• 2,779
1 vote

### Different types of pressure and their sources

Good morning. Pressure is understood as a concept in physics that represents force per unit area. In this way, it can relate substantially different concepts that have in common the existence of ...
• 75

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