posted by robert on .
A steel (Young's modulus 2.0 x 1011 N/m2) wire is strung between two supports attached to a ceiling. Initially, there is no tension in the wire when it is horizontal. A 88-N picture is then hung from the center of the wire, as the drawing illustrates, so the ends of the wire make angles of 26° with respect to the horizontal. What is the radius of the wire?
The wire stretches to a new length
L /cos26. The strain is
(1/cos26) - 1
Multiply that by Young's modulus for the stress in the wire.
The wire tension T is given by
T sin26 = 44 N
Use T and the stress to get the wire area and radius.