Stress

Stress = applied force on a surface divided by area over which the force is applied.

Tensile stress is "pulling".

Compressive stress is "pushing".

Stress in fluids

The stress in a point in a material is given by a stress tensor; three components (σ_xx, σ_yy and σ_zz) denote the stress along the three normals (speaking in a Cartesian coordinate system) and the remaining six components (σ_xy = σ_yx, σ_xz = σ_zx and σ_yz = σ_zy) denote the shear stress in the point.

In fluids that are at rest the components of the shear stress are always zero, which results in the components of the normal stress being equal to one another (σ_xx = σ_yy = σ_zz; the stress in the fluid is isotropic, this is Pascal's Law).

In fluids that are in motion the components of the shear stress are not zero and generally the stress in the fluid is also not isotropic, so it is not possible to speak of "the" normal stress in a point. However, it can be shown that the average of the three components of the normal stress taken in three perpendicular faces (in relation to each other) is independent of the orientation of these faces. This average equates to the isotropic part of the stress. The deviation of the components of the normal stress from this average is called the deviator stress. The shear stress belongs, in its entirety, to the deviator stress. The average of the components of the normal stress is given as follows:

σ₀ = 1/3 (σ_xx + σ_yy + σ_zz)

In mechanics the usual way to indicate the difference between tensile and compressive stress in mathematical notations is to denote tensile stress (pulling) with a positive value and compressive stress with a negative value. So, if one comes across a line that reads:

σ_cable = 600 [N]

this means that the tension in the (imaginary) cable is equivalent to the force needed to keep about 60 [kg] from falling to the earth.

In fluids and gasses, however, tensile stress is a very rare occurrence, and therefore the definition pressure (p) is introduced, which is equivalent to the isotropic part of the compressive stress in a fluid or gas:

p = - σ₀ = - 1/3 (σ_xx + σ_yy + σ_zz)

Variations in the isotropic part of the stress (tension or pressure) result in changes in the volume of the gas or fluid, while variations in the deviator stress result in changes in the shape of the gas or fluid (usually resulting in the fluid or gas being in motion).

Support write-up for Fluid mechanics

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July 8, 2001

(σ) experienced within a solid is the magnitude of the force acting F, divided by the area A over which it acts:

stress = force / area of surface on which force acts

σ = F / A

Its SI unit is the pascal (Pa), where 1 Pa = 1 N / m². Thus, if a cane supports a load of stress at any point within the cane is the load divided by the cross-sectional area at that point; the narrowest regions experience the greatest stress.

Stress killed me, it killed my mother. She maintains that still.
Her illness couldn't of helped, the worry it must have caused:
To abdicate a life because of that, is not only a burden for
My father, but also a massive issue for me; not discounting siblings.
Nuances of things past, gloat at my dysfunctional position,
Although, nothing is attained or released without prejudice.
Is this wicked sophistry I'm in ignorance of
Or just the tests that time presents?
Because of these problems, I find that kindness and generosity
Seem emotions with which I'm at most, ambivalent;
Token gestures, shallow movements, symbolise my outward self.
It's natural, in these cases, to realise that not only am I
The creator of this destruction; but also its designer.

Stress is the process by which we appraise and cope with environmental threats and challenges.

Things that provoke stress are called stressors. Three main types have been studied:

• Catastrophes: unpredictable, large-scale events, for example war and natural disasters.
• Significant life changes: leaving home, the death of a loved one, etc.
• Daily hassles: the little every day things.

Stress/shwag is also a slang term for low-grade weed. Stress can be discerned from higher grade weed by the following distinctive characteristics:

It will look and feel old and dry.

It won't look as fresh and green as mids or chronic.

It exhibits a rather insipid and unpleasant taste when smoked.

It's cheap as hell.

Most marijuana connoisseurs prefer chronic over mids or stress but there are some bud smokers who prefer the milder high induced by stress or mids(mid grade weed between stress and chronic). If you experience symptoms of high-anxiety or paranoia when smoking dank herb, you may want to try stress instead, it could also save you a lot of money as it is exponentially cheaper. However, many smokers complain of headaches, fatigue and stiffness due to smoking stress(giving aptness to the name).

The poorer quality of stress relative to chronic is due largely to the punishing abuse the herb is put through during it's preparation and distribution. Stress is usually grown in Mexico or Columbia by drug lords running large smuggling operations and care little about the quality of their weed. Most kids living in middle-class suburbia will never see stress in their lifetime. So, there is some truth when the government says "Smoking weed supports terrorism." But a more accurate statement would be "smoking bad weed supports terrorism." So just play it safe, smoke the chronic!

Stress (?), n. [Abbrev. fr. distress; or cf. OF. estrecier to press, pinch, (assumed) LL. strictiare, fr. L. strictus. See Distress.]

1.

Distress. [Obs.]

Sad hersal of his heavy stress.
Spenser.

2.

Pressure, strain; -- used chiefly of immaterial things; except in mechanics; hence, urgency; importance; weight; significance.

The faculties of the mind are improved by exercise, yet they must not be put to a stress beyond their strength.
Locke.

A body may as well lay too little as too much stress upon a dream.
L'Estrange.

3. (Mech. & Physics)

The force, or combination of forces, which produces a strain; force exerted in any direction or manner between contiguous bodies, or parts of bodies, and taking specific names according to its direction, or mode of action, as thrust or pressure, pull or tension, shear or tangential stress. Rankine.

Stress is the mutual action between portions of matter.
Clerk Maxwell.

4. (Pron.)

Force of utterance expended upon words or syllables. Stress is in English the chief element in accent and is one of the most important in emphasis. See Guide to pronunciation, §§ 31-35.

5. (Scots Law)

Distress; the act of distraining; also, the thing distrained.

Stress of voice, unusual exertion of the voice. --
Stress of weather, constraint imposed by continued bad weather; as, to be driven back to port by stress of weather. --
To lay stress upon, to attach great importance to; to emphasize. "Consider how great a stress is laid upon this duty." Atterbury. --
To put stress upon, or To put to a stress, to strain.

 

© Webster 1913

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Stress (?), v. t.

1.

To press; to urge; to distress; to put to difficulties. [R.] Spenser.

2.

To subject to stress, pressure, or strain.

 

© Webster 1913

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Stress (?), v. t.

1.

To subject to phonetic stress; to accent.

2.

To place emphasis on; to make emphatic; emphasize.

 

© Webster 1913