A monoatomic ideal gas, initially at temperature $T_1$, is enclosed in a cylinder fitted with a frictionless…

A monoatomic ideal gas, initially at temperature $T_1$, is enclosed in a cylinder fitted with a frictionless piston. The gas is allowed to expand adiabatically to a temperature $T_2$ by releasing the piston suddenly. If $L_1$ and $L_2$ are the lengths of the gas column before and after expansion respectively, then $\frac{T_1}{T_2}$ is given by
  1. L1/L22/3
  2. L1/L2
  3. L2/L1
  4. L2/L12/3

Solution

During adiabatic expansion, we know TVγ-1=constant

or   T1V1γ-1=T2V2γ-1

For a monoatomic gas,  γ = 5 3

∴         T1T2=V2V2γ-1=AL2AL15/3-1     (where A is the cross section area of the piston)

                          =L2L12/3

Asked in: MHT CET Full Test 10

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