Name: Al H.
Status: Other
Age: 60s
Location: N/A
Country: N/A
Date: February 2003
Question:
In the business I work in we had a discussion concerning
precise measuring blocks called "gage blocks". These are stacked up to
determine very close tolerances by rubbing (wringing) them together to
remove the air between the two surfaces. If a stack of gage blocks were
put into a vacuum, would the molecular attraction still hold them
together or would they fall apart since air pressure is the same on all sides?
Replies:
I do not quite understand what you are asking. The blocks are not held
together by the film of air between the blocks. However, it is difficult to
pull them apart rapidly, because doing so creates a vacuum between the
blocks until air can rush in from the edges of the gap. More precisely,
pulling the blocks apart involves pushing the atmosphere aside, which
requires substantial force (air pressure times surface area). If the blocks
were in a vacuum, they would not be so difficult to separate. Is that what
you are asking?
Richard E. Barrans Jr., Ph.D.
PG Research Foundation, Darien, Illinois
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