Q18 (b) A rod of length 1.05 m having negligible mass is supported at its ends by two wires of steel (wire A) and aluminium (wire B) of equal lengths as shown in Fig. 9.15. The cross-sectional areas of wires A and B are
respectively. At what point along the rod should a mass m be suspended in order to produce equal strains in both steel and aluminium wires.
Cross-Sectional Area of wire A is AA = 1 mm2
Cross-Sectional Area of wire B is AB = 2 mm2
Let the Mass m be suspended at y distance From the wire A
Let the Tension in the two wires A and B be FA and FB respectively
Since the Strain in the wires is equal
Equating moments of the Tension in the wires about the point where mass m is suspended we have
The Load should be suspended at a point 43.2 cm from the wire A such that there is an equal strain in the two wires.