Properties Of Solids And Liquids Question 116

Question: Three rods of equal length l are joined to form an equilateral triangle PQR. O is the mid point of PQ. Distance OR remains same for small change in temperature. Coefficient of linear expansion for PR and RQ is same i.e. α2 but that for PQ is α1 . Then

Options:

A) α2=3α1

B) α2=4α1

C) α1=3α2

D) α1=4α2

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Answer:

Correct Answer: D

Solution:

(OR)2=(PR)2(PO)2=l2(l2)2

=[l(1+α2t)]2[l2(1+α1t)]2

l2l24=l2(1+α22t2+2α2t)l24(1+α12t2+2α1t)

Neglecting α22t2

and α12t2

0=l2(2α2t)l24(2α1t)2α2=2α14;α1=4α2



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