An empty balloon weighs $1\, g$. The balloon is filled with water to the neck and tied with  a massless thread. The weight of balloon alongwith water is $101\, g$. The balloon filled with  water is weighed when fully immersed. Then, its weight in water is …… $g$

A solid sphere of specific gravity $27$ has a concentric spherical cavity and it just sinks in water. The ratio of cavity radius to that of outer radius of sphere is

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

Two cubes of size $1.0$ $m$ sides, one of relative density $0.60$ and another of relative density $=$ $1.15$ are connected by weightless wire and placed in a large tank of water. Under equilibrium the lighter cube will project above the water surface to a height of …….. $cm$

Construction of submarines is based on