## Sheer vs. Shear

I recently saw a reference to “sheer waves” in a geophysics report. The author really meant “shear waves.”

Sheer means “nearly transparent,” as in sheer curtains that let the light in. Think “see-through,” which also has a double E.

Shear means “to cut,” as with shears or scissors. Think of the A in SHEARS as resembling a pair of scissors in shape.

Sheer also has the following usages and meanings:

•       Sheer stupidity – utter or unqualified stupidity

•       Sheer joy – pure or unadulterated joy

•       Sheer determination – acting solely or only with determination

•       Sheer cliff – a very steep cliff Note that sheer is used as an adjective in these meanings.

Shear, on the other hand, is used as a noun or verb, not an adjective. A shear force, or a shearing force, is defined by Webster as “an internal force tangential to the section on which it acts.” This is what is meant by a shear wave in seismic parlance.

Shear is also “an action or stress resulting from applied forces that causes or tends to cause two contiguous parts of a body to slide relatively to each other in a direction parallel to their plane of contact.” This is what is meant when measuring viscosity using a Brookfield viscometer and increasing the shear rate by speeding up the rotating bob in the cup of liquid.

So now that you know the difference, it would be sheer stupidity to use “sheer” instead of “shear” when talking about waves or forces.
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Profound Quotes of the Day:

“It is the duty of a good shepherd to shear his sheep, not to skin them.”

– Tiberius Caesar, Roman statesman, 42 BC – 37 AD

“If people ask me for the ingredients of success, I say one is talent, two is stubbornness or determination, and third is sheer luck. You have to have two out of the three. Any two will probably do.”

– Fred Saberhagen, American author, b. 1930

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