Talk:Pressure-gradient force

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Factual error: Pressure[edit]

The page states that pressure is a force per mass. Pressure is a measurement of force per area, is it not? Nschoem 01:13, 2 May 2008 (UTC)

Hey - it's actually NEGATIVE 1/rho * grad P --- pressure pushed in the opposite direction of the gradient (from high to low pressure, not the other way around)..... I fixed the error... (this is also in the Stull book referenced here) Here's the math:

$F=dP\cdot dA=(P_{o}-P_{o+dz})\cdot dA={\frac {-dP}{dz}}dz\cdot dA$

${\frac {-dP}{dz}}dz\cdot dA=\rho \cdot dA\cdot dz\cdot a$

${\frac {-dP}{dz}}=\rho \cdot a$

-yano, 5/11/14

This concept is not restricted to air masses and earth-atmosphere effects. This page is linked in Hydrostatic equilibrium, the balance of gravitational effects with pressure gradient (i.e. why the sun is a relatively constant shape and size) Longillo (talk) 19:10, 20 January 2010 (UTC)[reply]

Conceptual Assumption[edit]

This article assumes that the force acting on the gas is only acting on the gas, and so the acceleration can be substituted using F=m*a. However this is only true for a very small amount of cases. It's a little misleading, even if it is true in some cases, to state the formula directly as this equation. Just saying.

Jondoge (talk) 12:58, 30 September 2014 (UTC)[reply]