RE: [ATM] RE: Berry's 10-inch telescope plans

["Donald Good" <donald.good@comcast.net>]

The resonant frequency is dependent on both stiffness (strength of material
and dimensions)(proportional) and weight (inversely proportional).  The
reason that the styrofoam has a high "ring" is that to compensate for its
low stiffness, it also has low weight.  So comparing plywood to styrofoam
"ring" is like comparing apples to oranges.  Since Tom Krajci wrote that he
was comparing plywood sheets of the same dimensions (e.g. 4'x4'x3/4"),
probably of similar weights, the higher tone indicating higher stiffness is
a fair approximation.  Factoring in the weight too, would give a better
approximation.

Don

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