If a bar is made of copper whose coefficient of linear expansion is one and a half times that of iron, the ratio of 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 of copper may be taken to be equal to that of iron) is

Options

A. `3//2`
B. `2//3`
C. `9//4`
D. `4//9`

Answer

A

Explanation

`F=Y alpha t A or F prop alpha`
(`because ` Y t A is same for both copper and iron)
or `F_(C ) prop alpha_(C ) and F_(1) prop alpha_(1) therefore (F_(C ))/(F_(I))=(3//2)/(1)= (3)/(2)`