Physics · 2026
JEE Main · 22 January 2026, Shift 1 · Q34
A cylindrical tube A B of length l, closed at both ends contains an ideal gas of 1 mol having molecular weight M. The tube is rotated in a horizontal…
A cylindrical tube $\displaystyle A B$ of length $\displaystyle l$, closed at both ends contains an ideal gas of $\displaystyle 1$ mol having molecular weight $\displaystyle M$. The tube is rotated in a horizontal plane with constant angular velocity $\displaystyle \omega$ about an axis perpendicular to $\displaystyle A B$ and passing through the edge at end $\displaystyle A$, as shown in the figure. If $\displaystyle P_A$ and $\displaystyle P_B$ are the pressures at $\displaystyle A$ and $\displaystyle B$ respectively, then
(Consider the temperature is same at all points in the tube)

Official answer
From NTA’s final answer key for this paper.
(1)
$\displaystyle P_B=P_A \exp \left(M \omega^2 l^2 / 2 R T\right)$
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JEE Main 2026 Physics question, with the answer from NTA’s final answer key. Where our answers come from.