A cylindrical block of wood of base area $30\ cm^2$ , floats in a liquid of density $900\ kg/m^3$ . The block is depressed lightly and then released. The time period of the resulting oscillations of the block is equal to that of spring with block of same mass, then spring constant is equal to ........ $N/m$
If $W$ be the weight of a body of density $\rho $ in vacuum then its apparent weight in air of density $\sigma $ is
Two pieces of metal when immersed in a liquid have equal upthrust on them; then
A very large block of ice of the size of a volleyball court and of uniform thickness of $8 \,m$ is floating on water. A person standing near its edge wishes to fetch a bucketful of water using a rope. The smallest length of rope required for this is about ............... $m$
A metallic body of material with density of $8000\ kg/m^3$ has a cavity inside. A spring balance shows its mass to be $10.0\ kg$ in air and $7.5\ kg$ when immersed in water. The ratio of the volume of the cavity to the volume of the material of the body must be