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What is the formula for pressure?

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ustaad | Student, Grade 9 | eNoter

Posted December 24, 2009 at 2:01 PM via web

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What is the formula for pressure?

Tagged with formula, physic, pressure, science

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pohnpei397 | College Teacher | (Level 3) Distinguished Educator

Posted December 24, 2009 at 2:12 PM (Answer #1)

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The formula for pressure is

P = F/A

In this equation, P stands for pressure while F stands for force and A stands for area.  Pressure is typically measured in a unit called the Pascal.

So what this means is that the amount of pressure that is exerted on an area is determined by the size of that area and by the amount of force that is pressing against it.

Therefore, if you have a given amount of force, you will have more pressure if it presses down on a small area than if it presses down on a large area.

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neela | High School Teacher | Valedictorian

Posted December 25, 2009 at 1:38 AM (Answer #2)

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Pressure is defined as the normal force per unit area of a surface. If F is the force acting normal to the surface area A,then the pressure P is given by :

P = F/A, Newtons/square meter or P = F/A Pascals.

According to the dimensional analysis of the pressure from this definition is: Force/Area = [M^1]*[L^1][T^(-2)]/[L^2]

= [M^1][L^(-1)][T^(-2)], where M  represents mass, L represents length and T represents time in fundamental  standard units.




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giorgiana1976 | College Teacher | Valedictorian

Posted December 25, 2009 at 7:30 PM (Answer #3)

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Pressure (symbol: p) is the force applied per unit area,  in the direction perpendicular to that surface.

P=F/A, where, F is the normal force, A is the area.

Pressure is a scalar, which in IS is measured in pascals.

1 Pa = 1 N/m2

The pressure is transmitted to surrounding areas or sections of the field of fluid, in the normal direction at any point in these areas or sections.

It is a fundamental parameter in thermodynamics and is a joint variable to volume.

Characteristic Cases

Static pressure

Static pressure, usually denoted SP, is the inner pressure of a fluid which is measured with a device that moves with the same speed as the fluid. For example, to the walls of a pipeline is carried the static pressure of fluid flowing through it.

Dynamic Pressure

Dynamic pressure is the additional pressure of a fluid that would hit an area and would be forced to consume completely it's kinetic energy. It is expressed by the relation:

p dynamic= rho*(v^2/2)

where rho is fluid density in kg/m^3, v is velocity in m / s.

Stagnation pressure

Stagnation pressure is the pressure that would exert a fluid in motion if it were forced to stop. If a fluid moves faster, its stagnation pressure increases. Static pressure and stagnation pressure are related to Mach number of fluid. See also Bernoulli's equation, which however is  valid only for incompressible fluids.Pressure of a fluid in motion can be measured with a Pitot tube, connected to a manometer.

 Hydrostatic pressure

Hydrostatic pressure is the pressure due to the weight of a fluid.



ρ (rho) is density of the fluid (eg water density is almost 1000 kg/m3);

g is the acceleration due to gravity (conventional, 9.80665 m/s2 to the sea surface);

h is the height of column of liquid (in meters).

Pressure of explosion or deflagration

Explosion or deflagration pressures are created by igniting explosive gas, aerosol, suspension in closed or open spaces. These pressures propagate as a wave of shock.

Negative pressures

While pressures are generally positive, in some cases negative pressures are meet:

-When discussing the relative pressures. For example, an absolute pressure of 80 kPa may be expressed as a relative pressure of -21 kPa (ie 21 kPa under atmospheric pressure of 101 kPa). The technique is called "a depression of 21 kPa.

- When attractive forces (eg Van der Waals forces) between particles of fluid, exceeds the forces of rejection. This scenario, however, is unstable because the particles are closer and closer until rejection forces would balance the forces of attraction.

- Negative pressures occurring during plant transpiration.

-Casimir effect can create small forces of attraction by interacting with vacuum energy. Sometimes this is called 'vacuum pressure' (not to be confused with depression).

- Depending on the reference system to surface orientation, a positive pressure on one side of a surface can be considered negative on the other side of the area.

- In cosmology( dark energy, expansion of the universe).

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mkcapen1 | Middle School Teacher | Valedictorian

Posted December 24, 2009 at 4:20 PM (Answer #4)

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Pressure is often listed as psi.  The formula to measure pressure is Pressure equals force in pounds over the area in square inch.  The written abbreviated formula is P= F/A.

By looking at the formula one can see that top obtain the pressure on an object, one must divide the the force by the area of an object.

All fluids, liquids, and gases omit pressure.  If a fluid is not moving it exerts even pressure.  Air pressure is measured by using a barometer.

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astrosonuthird | Student | Valedictorian

Posted October 22, 2012 at 12:34 PM (Answer #5)

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The formulae for pressure is P= F/A




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alejandrogalarce | Student , Undergraduate | Valedictorian

Posted October 12, 2013 at 5:46 PM (Answer #6)

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Pressure is the amount of force acting perpedicularly per unit area. The symbol of pressure is p.



p is the pressure

F is the normal force

A is the area of the surface on contact.

Pressure is a scalar quantity. It relates the vector surface element (a vector normal to the surface) with the normal force acting on it. The pressure is the scalar proportionality constantthat relates the two normal vectors.


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laurto | Student , Grade 10 | eNoter

Posted December 7, 2013 at 8:08 PM (Answer #7)

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p= pressure

F= normal force

A= area of surface on contact

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laurto | Student , Grade 10 | eNoter

Posted December 10, 2013 at 8:05 PM (Answer #8)

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p= F/A

p= pressure

F= force

A= area

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Yojana_Thapa | Student , Grade 10 | eNoter

Posted January 25, 2014 at 10:35 PM (Answer #9)

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Pressure= Force/Area

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parama9000 | Student , Grade 11 | Valedictorian

Posted January 26, 2014 at 2:11 PM (Answer #10)

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Jyotsana | Student , Grade 10 | eNoter

Posted February 21, 2014 at 4:15 AM (Answer #11)

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Pressure = Force/Area

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nicole8923 | Student , Grade 10 | eNoter

Posted February 26, 2014 at 7:27 PM (Answer #12)

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The formula for pressure is P= F/A

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