$A$ solid sphere of radius $r$ is floating at the interface of two immiscible liquids of densities $\rho_1$ and $\rho_2$ $(\rho_2 > \rho_1)$,with half of its volume lying in each. The height of the upper liquid column from the interface of the two liquids is $h$. The force exerted on the sphere by the upper liquid is (atmospheric pressure $= p_0$ and acceleration due to gravity is $g$).

Four identical beakers contain the same amount of water as shown below. Beaker $A$ contains only water. $A$ lead ball is held submerged in beaker $B$ by a string from above. $A$ same-sized plastic ball,say a table tennis $(TT)$ ball,is held submerged in beaker $C$ by a string attached to a stand from outside. Beaker $D$ contains a same-sized $TT$ ball which is held submerged by a string attached to the bottom of the beaker. These beakers (without the stand) are placed on weighing pans and register readings $w_{A}, w_{B}, w_{C}$,and $w_{D}$ for $A, B, C$,and $D$,respectively. Effects of the mass and volume of the stand and string are to be neglected.

Two non-mixing liquids of densities $\rho$ and $n\rho$ $(n > 1)$ are put in a container. The height of each liquid is $h$. $A$ solid cylinder of length $L$ and density $d$ is placed in this container. The cylinder floats with its axis vertical and a length $pL$ $(p < 1)$ submerged in the denser liquid. The density $d$ is equal to:

An ice cube contains a large air bubble. The cube is floating on the horizontal surface of water contained in a trough. What will happen to the water level when the cube melts?

The reading of a spring balance when a block is suspended from it in air is $60\,N$. This reading changes to $40\,N$ when the block is immersed in water. The specific density (relative density) of the block is:

$A$ person is sitting in a boat floating in a lake. This person fills a bucket of water from the lake and puts it in the boat. Will the water level in the lake go down? Explain.