Skip to main content
36 votes

Why is pressure in the outermost layer of a star lower than at its center?

Considering the only force keeping the star together is gravitational in nature, Gravity is also what's keeping our oceans stuck to the Earth's surface. Where's the pressure at its highest, near sea ...
Flater's user avatar
  • 890
17 votes
Accepted

Why is pressure in the outermost layer of a star lower than at its center?

There is a lot of mass above the centre, pushing down on it. On the surface there is no mass above. Hence you get high pressure at the centre and zero at the surface.
Anders Sandberg's user avatar
7 votes

Why is pressure in the outermost layer of a star lower than at its center?

This is an exercise in hydrostatics. Imagine the sun consisting of a sphere of water. The deeper you go beneath the surface, the more water weight you have bearing down on you from above, and the ...
niels nielsen's user avatar
6 votes

Why is pressure in the outermost layer of a star lower than at its center?

Perhaps the confusion in the question arises because you are thinking of a rigid spherical shell of constant density, and you know that inside such a shell the gravitational field is zero? A ball of ...
C.M.O.B.'s user avatar
4 votes

Why is pressure in the outermost layer of a star lower than at its center?

I believe you are confusing "force of gravity" with "pressure." The gravitational pull (or local acceleration $g$) is indeed zero at the center of the Sun, and a maximum elsewhere ...
RC_23's user avatar
  • 9,500
4 votes

What would happen if the sun became the size of the earth?

The ideal gas law gives a first hint of trouble: if you compress gas by a factor of $(r_{sun}/r_{earth})^3\approx 100^3=10^6$, you should expect the temperature to go up by a factor of a million if ...
Anders Sandberg's user avatar
4 votes

Proportionality of Pressure and Temperature in defining Absolute Temperature scale

In defining the ideal gas temperature scale, it is assumed that the pressure of the gas at constant volume is proportional to the temperature $T$. How can we verify whether this is true or not? Are we ...
naturallyInconsistent's user avatar
2 votes
Accepted

How does Shear Force on a fluid in a vessel reaches an equilibrium if molecules are free to make contact?

The force being always perpendicular to the walls is not contradictory with the impact being not perpendicular. Think of a billiard table without friction. The angle of incidence will be equal to the ...
Claudio Saspinski's user avatar
1 vote

Can siphons improve the efficiency of hydroelectric dams?

No, you cannot gain any efficiency. Remember the bernoulli equation: $P_1 + \frac12\rho v_1^2 + \rho gh_1 = P_2 + \frac12\rho v_2^2 + \rho gh_2$ If you have water at rest at $P_{atm}$ on the top, and ...
Pato Galmarini's user avatar
1 vote

Why will low pressure pulling higher pressure air towards it make "thrust"?

Low pressure air means a lack of air molecules. Normal pressure air means a normal amount of air molecules. Low pressure means that the combination of the number of molecules and the speed of the ...
BowlOfRed's user avatar
  • 41k
1 vote
Accepted

Understanding Pressure Transmission and Lift Mechanics in a Hydraulic Lift

First: pressure in fluids an gases is the same in all direction, so your "downward pressure does not exist. Say the thin tube is left, so you have a downward force F1 on the left piston, this ...
trula's user avatar
  • 6,362
1 vote

Is there any formula for calculating the temperature required for nuclear fusion for a specific pressure?

Key to getting the answer you wish is first knowing what the equation of state is for the fusion reactants. This lets you relate pressure, temperature, and density. Please note that all equations of ...
niels nielsen's user avatar
1 vote
Accepted

Work performed by hydrostatic pressure

With a little less math, the power of a stress distribution $\mathbf{t}_n$ over the boundary of a volume $V$ is $$P(t) = \oint_{\partial V} \mathbf{t}_n \cdot \mathbf{u} \ ,$$ being $\mathbf{u}$ the ...
basics's user avatar
  • 10.7k

Only top scored, non community-wiki answers of a minimum length are eligible