Useless Straw, They Said!

For an object to remain at rest, the net force acting on it should be 0. The straw we used in both of the cases was the same. This straw has its weight acting on it downwards. And, the buoyant force of the liquid which counters the weight is acting upwards. So, in both the cases the buoyant forces are equal. Now, $\rho_{w}V_{w}g=\rho_{l}V_{l}g$ [From Archimedes' Principle] where $V_{w}$ is the volume of the straw immersed in water, $V_{l}$ is the volume of the straw immersed in lemonade, $\rho_{w}$ is the density of water and $\rho_{l}$ is the density of lemonade. Now, $V_{w}=0.54V$ and $V_{l}=0.45V$ can be substituted into the above equation. [ $V$ is the total volume of the straw] $\rho_{w}(0.54V)g=\rho_{l}(0.45V)g$ or, $\rho_{l}=\rho_{w}\times\frac{0.54}{0.45}$ or, $\rho_{l}=1200 kg/m^3$