JEE Main 2026 Jan 23 Shift 2, Physics Q25: Kinetic Theory of an Ideal Gases

JEE Main2026Jan 23, Shift 2Physics

The velocity of sound in air is doubled when the temperature is raised from $0^{\circ} C$ to $α^{\circ} C$ . The value of $α$ is ______.

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Solution

Speed of sound in an ideal gas: $v = \frac{γ R T}{M}$ , so $v \propto T$ (T in kelvin).

$\frac{v _{0}}{v _{1}} = \frac{T _{1}}{T _{2}} \Rightarrow \frac{1}{2} = \frac{273}{T _{2}}$

$T_{2} = 4 \cdot 273 = 1092$ K $= 819^{\circ} C$ .

$∴ α = 819$ .

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