Question

A cubic vessel (with faces horizontal + vertical) contains an ideal gas at NTP. The vessel is being carried by a rocket which is moving at a speed of 500m s^-1 in vertical direction. The pressure of the gas inside the vessel as observed by us on the ground

(a) remains the same because 500ms^-1 is very much smaller than v_rms of the gas.

(b) remains the same because motion of the vessel as a whole does not affect the relative motion of the gas molecules and the walls.

(c) will increase by a factor equal to  (V²_rms (500)²) /  V²_rms  where V_rms was the original mean square velocity of the gas.

(d) will be different on the top wall and bottom wall of the vessel.

Answer 1

(b) Remains the same because motion of the vessel as a whole does not affect the relative motion of the gas molecules and the walls.

Comment for discussion: This brings in concepts of relative motion and that when collision takes place, it is the relative velocity which changes.