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Q8.4: NCERT Physics - Part 2 MECHANICAL PROPERTIES OF SOLIDS 8.4 Solution: Read the following two statements below carefully and state,…
⚠️ Common Exam Traps & Conceptual Pitfalls
Students often assume that the axial extension of a helical spring is governed by Young’s modulus, but the wire undergoes torsional shear, so the spring’s stiffness depends on the shear modulus; likewise, rubber’s large strain under a given stress gives it a much lower Young’s modulus than steel, despite its apparent elasticity.
Read the following two statements below carefully and state, with reasons, if it is true or false. (a) The Young's modulus of rubber is greater than that of steel; (b) The stretching of a coil is determined by its shear modulus.
Step-by-Step Verified Solution
**Answer:** (a) False (b) True
**Step-by-Step Explanation:**
(a) False. For the same stress, rubber undergoes much larger strain than steel. Since , rubber has a smaller Young's modulus than steel [citation:11][citation:36].
(b) True. When a coil is stretched, the wire undergoes twisting, which is a shear deformation. Hence, the stretching of a coil is determined by its shear modulus [citation:11][citation:36].
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