Two elastic rods are joined between fixed supports as shown in the figure. The condition for no change in the lengths of individual rods with the increase of temperature is: (α1,α2 = linear expansion coefficient, A1, A2 = area of rods, Y1,Y2 = Young's modulus)

Correct answer: D. A1/A2 = (α2 * Y2) / (α1 * Y1)

  • A. A1/A2 = (α1 * Y1) / (α2 * Y2)
  • B. A1/A2 = (L1 * α1 * Y1) / (L2 * α2 * Y2)
  • C. A1/A2 = (L2 * α2 * Y2) / (L1 * α1 * Y1)
  • D. A1/A2 = (α2 * Y2) / (α1 * Y1)

Explanation

The correct answer is d) A1/A2 = (α2 * Y2) / (α1 * Y1)For no change in length, the compressive force in both rods should be equal:A1 * Y1 * α1 * ΔT = A2 * Y2 * α2 * ΔT=> A1/A2 = (α2 * Y2) / (α1 * Y1)

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