One end of a metal wire is fixed to a ceiling and a load of 2 kg hangs from the other end. A similar wire is attached to the bottom of the load and another load of 1 kg hangs from this lower wire. Then the ratio of longitudinal strain of upper wire to that of the lower wire will be . [Area of cross section of wire =0.005 cm2, Y=2 1011 Nm-2 and g=10 ms-2]
Answer
3
Solution
[figure]
Upper wire holds both loads: T1=(2+1) 10=30 N; lower wire: T2=1 10=10 N
Strain = FAY ( same A and Y strain F)
strain1strain2= 3010=3
Answer: 3