A copper wire of length 2.2 m and a steel wire of length 1.6m, both of diameter 3mm are connected end to end. When stretched by a load, the net elongation is found to be 0.70 mm. Obtain the load applied.(Y_(s)=2.0xx10^(11)Nm^(-2)) (Y_(c)=1.1xx10^(11)Nm^(-2))

A copper wire of length 2.2 m and a steel wire of length 1.6m, both of

1.	A copper wire of length 2.2 m and a steel wire of length 1.6m, both of diameter 3mm are connected end to end. When stretched by a load, the net elongation is found to be 0.70 mm. Obtain the load applied.(Y_(s)=2.0xx10^(11)Nm^(-2)) (Y_(c)=1.1xx10^(11)Nm^(-2))
Answer» `1.8xx10^(2)N` `1.2XX10^(2)N` `3.2xx10^(4)N` `2.4xx10^(2)N` Solution :Both copper and steel wires are under the same tensile stress, as the tension and area of cross-section of the wires are same. `RARR""(W)/(A)=Y_(c)XX((DeltaL_c)/(L_c))=Y_(s)xx((DeltaL_s)/(L_s))` `rArr""(DeltaL_c)/(DeltaL_s)=((Y_s)/(Y_c))xx((L_c)/(L_s))` `=((2xx10^(11)Nm^(-2))/(1.1xx10^(11)Nm^(-2)))((2.2m)/(1.6m))` `=2.5` Also, `DeltaL_(c)+DeltaL_(s)=7xx10^(-4)m` `rArr""DeltaL_(c)=5xx10^(-4)m` `THEREFORE""W=(AxxY_(c)xxDeltaL_c)/(L_c)` `=(pi(1.5xx10^(-3)m)^(2)xx(1.1xx10^(11)Nm^(-2)xx5xx10^(-4)m))/(2.2m)` `=1.8xx10^(2)N`