Q. If a bar is made of copper whose coefficient of linear expansion is one and a half times that of iron, the ratio of the force developed in the copper bar to the iron bar of identical lengths and cross-sections, when heated through the same temperature range (Young’s modulus for copper may be taken equal to that of iron) is
A) 3/2
B) 2/3
C) 9/4
D) 4/9
Explanation
(a) $F = YA\alpha T\ ;\ $
$\frac{F_{Cu}}{F_{Fe}} = \ \frac{\alpha_{Cu}}{\alpha_{Fe}} = \frac{3}{2}\ $
Reviewed by Dr. Abubacker
Physics Educator & NEET/JEE Specialist
Ph.D. in Physics with 19+ years of teaching experience.