A spherical balloon of volume $V$ is filled with helium, which has a density $\rho_{He}$. The balloon is connected to the bottom of a box by an ideal cord. Initially, the space around the balloon is filled with argon gas, which has a density $\rho_{Ar}$, and the tension in the rope is measured. If the argon were removed and replaced with Krypton gas (density $\rho_{Kr}$), would the tension in the rope increase or decrease? You may assume that $\rho_{He} < \rho_{Ar} < \rho_{Kr}$.
Increase
Decrease
Give an expression for the magnitude of the change in the tension, in terms of given variables and the free-fall acceleration $g$.
$\Delta T=$