Physics - Heat & Thermo Question with Solution | TestHub
PhysicsHeat & ThermoThermal ExpansionMedium2 minQB
PhysicsMediumstatement
A rubber band is held stretched by a fixed weight and is then warmed gently. Which describes what happens and why? Statement I: It shortens, because stronger sideways thermal vibrations make the chains coil up more. Statement II: It lengthens, because the polymer chains expand like a normal solid.
Options:
Answer:
B
Solution:
Under tension, the elastic restoring force of rubber comes from the tendency of polymer chains to coil (entropic effect). Higher temperature increases the sideways vibration of the chain segments, which pulls the ends together, so the stretched band shortens. Bond-stretching expansion is much smaller. Statement I is true and Statement II false. Correct option: (B).
Subject:PhysicsTopic:Heat & ThermoSubtopic:Thermal Expansion
⏱ 2mℹ️ Source: QB
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