[CAUT] Wire Stretch

[RicB]

Okay guys...

Heres what I come up with.  I'm going to assume a Youngs modulus for 
piano wire in accordance with McFerrin, which is the lowest I've run 
into so far out there.

For a 0.8 mm Ø string of 150 mm long speaking length, 50 mm back 
length... and tension at 150 with zero deflection, a 5 mm deflection 
will increase tension to 189 lbs, cause a frequency change of 248 hz 
(from 2057 to 2305) and impose a 28 lb bearing force on the point of 
deflection.

For a string of