Question

Two rods of equal length (0.45 cm) and diameter (1.5 cm) are placed end to end. One rod is aluminum, the other is brass. If a compressive force of 8400 N is applied to the rods, how much does their combined length decrease?

Answer 1

$\delta=\Sigma\frac{Fl_i}{E_iS}=\frac{4Fl}S(\frac 1{E_1}+\frac 1{E_2})=0.48~mm.$