A concrete slab of uniform thickness weighs 20,000 lb and is supported by two steel rods,...

A concrete slab of uniform thickness weighs 20,000 lb and is supported by two steel rods, as shown. The initial length of rod AB is 2 ft. The initial length of rod CD is 3 ft. Rod AB has an area of 1 in.2 and rod CD has an area of 2 in2. Calculate

(a) the elongation of each rod.

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(b) the required ratio of the areas of AB and CD so that the elongation of each bar is the same.

Problem