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MHT CET 2026 (15 Apr, Shift 2) · Thermodynamic Processes

Thermodynamic Processes question from MHT CET 2026 (15 Apr, Shift 2)

Q34MHT CET 2026 · 15 APR · SHIFT 2Medium

Thermodynamic Processes

An ideal gas is expanded adiabatically. How many times has the gas to be expanded to reduce the r.m.s. speed of molecules 3 times? (γ=1.5\gamma = 1.5)

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Answer: (d)

  1. vrms∝Tv_{rms} \propto \sqrt{T}: reducing it 3 times needs T2=T19T_2 = \frac{T_1}{9}.
  2. Adiabatic: TV1/2=TV^{1/2} = constant, so (V2V1)1/2=9\left(\frac{V_2}{V_1}\right)^{1/2} = 9.
  3. V2V1=81\frac{V_2}{V_1} = 81
  4. So the answer is (d) 81 times.
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