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← JEE Main 2026 · 4 Apr · Shift 2
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JEE Main 2026 · 4 Apr · Shift 2, Physics question 31

A metal string AA is suspended from a rigid support and its free end is attached to a block of mass MM. Second block having mass 2M2M is suspended at the bottom of the first block using a string BB. The area of cross sections of strings AA and BB are same. The ratio of lengths of strings of AA to B is 2 and the ratio of their Young's moduli (YA/YBY_A/Y_B) is 0.5. The ratio of elongations in AA to B is ________.

Choose one option
Answer and worked solution

Official answer: D

Tensions. String A holds both blocks (3Mg3Mg); string B holds 2Mg2Mg.

Elongation ratio. ΔL=TLAY\Delta L=\dfrac{TL}{AY}, so
ΔLAΔLB=32⋅2⋅10.5=6.\frac{\Delta L_A}{\Delta L_B}=\frac32\cdot2\cdot\frac1{0.5}=6.

(D)