$A$ certain block weighs $15 \ N$ in air. It weighs $12 \ N$ when immersed in water. When immersed in another liquid,it weighs $13 \ N$. The relative density of the block is:

Construction of submarines is based on

$A$ streamlined body falls through air from a height $h$ on the surface of a liquid. If $d$ and $D$ $(D > d)$ represent the densities of the material of the body and the liquid respectively,then the time after which the body will be instantaneously at rest is:

$A$ vessel filled with water is kept on a weighing pan and the scale is adjusted to zero. $A$ block of mass $M$ and density $\rho$ is suspended by a massless spring of spring constant $k$. This block is submerged into the water in the vessel. What is the reading of the scale?

$A$ ball rises to the surface at a constant velocity in a liquid whose density is $3$ times greater than that of the material of the ball. The ratio of the force of friction acting on the rising ball to its weight is (in $: 1$)

$A$ cubical block is floating in a liquid with one-fourth of its volume immersed in the liquid. If the whole system accelerates upward with an acceleration of $g / 4$,what will be the fraction of the volume immersed in the liquid?