A brass rod of length 50 cm and diameter 3.0 mm is joined to a steel rod of the same length and diameter. What is the change in length of the combined rod at 250 ^(@) C. if the original lengths are at 40.0 ^(@) C? Is there a "thermal stress developed at the junction ? The ends of the rod are free to expand (Co-efficient of linear expansion ofbrass = 2.0 xx 10^(-5) K^(-1) , " steel " = 1.2 xx 10^(-5) K^(-1)).

A brass rod of length 50 cm and diameter 3.0 mm is joined to a steel r

1.	A brass rod of length 50 cm and diameter 3.0 mm is joined to a steel rod of the same length and diameter. What is the change in length of the combined rod at 250 ^(@) C. if the original lengths are at 40.0 ^(@) C? Is there a "thermal stress developed at the junction ? The ends of the rod are free to expand (Co-efficient of linear expansion ofbrass = 2.0 xx 10^(-5) K^(-1) , " steel " = 1.2 xx 10^(-5) K^(-1)).
Answer» Solution :SINCE the ends of the combined rod are not clamped, each rod expands freely. `Delta l_("brass ") = 0.21 cm, Delta l_("steel") = 0.126 cm = 0.13 cm` TOTAL change in length ` = 0.34` cm. No .THERMAL stress. is DEVELOPED at the junction since the rods freely EXPAND.