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 $500 m/s$ in vertical direction. The pressure of the gas inside the vessel as observed by us on the ground

remains the same because $500 m/s$ is very much smaller than $v_{rms}$ of the gas 

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

will increase by a factor equal to $\left[{v^2}_{rms}+{\left(500\right)}^2\right]/{v^2}_{rms}$ , where $v_{rms}$ was the original mean square velocity of the gas

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