JEE Mains · Physics · STD 11- 8. mechanical properties of solids
A metal string \(A\) is suspended from a rigid support and its free end is attached to a block of mass \(M\). Second block having mass \(2M\) is suspended at the bottom of the first block using a string \(B\). The area of cross sections of strings \(A\) and \(B\) are same. The ratio of lengths of strings of \(A\) to \(B\) is \(2\) and the ratio of their Young's moduli \((Y_A/Y_B)\) is \(0.5\). The ratio of elongations in \(A\) to \(B\) is ______.
- A \(1\)
- B \(4\)
- C \(8\)
- D \(6\)
Answer & Solution
Correct Answer
(D) \(6\)
Step-by-step Solution
Detailed explanation
Tension in string \(B\) is due to the block of mass \(2M\): \(T_B = 2Mg\) Tension in string \(A\) is due to both blocks of mass \(M\) and \(2M\): \(T_A = Mg + 2Mg = 3Mg\) The elongation in a string is given by Hooke's law as \(\Delta L = \dfrac{TL}{AY}\). The ratio of…
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