An ornament weighs $10\, g$ in air and $6\, g$ in water. The density of the material of the ornament is $20\, g/cc$. The volume of the cavity in the ornament is ........ $cc$.

An object suspended by a wire stretches it by $10 \,mm$. When the object is immersed in a liquid,the elongation in the wire reduces by $\frac{10}{3} \,mm$. The ratio of the relative densities of the object and the liquid is ............

An object of mass $10 \ kg$ is released from rest in a liquid. If the object moves a distance of $2 \ m$ while sinking in a time duration of $1 \ s$,then the mass of the liquid displaced by the submerged object is $(g = 10 \ m/s^2)$. (in $kg$)

$A$ boat having a length of $3\,m$ and breadth $2\,m$ is floating on a lake. The boat sinks by $1\,cm$ when a man gets on it. The mass of the man is ....... $kg$. (Take density of water $\rho = 1000\,kg/m^3$ and $g = 10\,m/s^2$)

$A$ wooden piece floats half-submerged in a tub of water. If the system is transferred to a lift ascending with acceleration $a$,the wooden piece will:

$A$ wooden block with a coin placed on its top floats in water as shown in the figure. $l$ and $h$ are as shown. After some time,the coin falls into the water. Then: