$A$ wooden block of volume $1000\, cm^3$ is suspended from a spring balance. It weighs $12\, N$ in air. It is suspended in water such that half of the block is below the surface of water. The reading of the spring balance is ...... $N$.

$A$ large ship can float but a steel needle sinks because of

$A$ solid floats such that its $(1/3)$rd part is above the water surface. Then,the density of the solid is

$A$ tub is filled with water and a wooden cube $10 \ \text{cm} \times 10 \ \text{cm} \times 10 \ \text{cm}$ is placed in the water. The wooden cube is found to float on the water with a part of it submerged in water. When a metal coin is placed on the wooden cube,the submerged part is increased by $3.87 \ \text{cm}$. The mass of the metal coin is . . . . . . gram. (Take water density as $1 \ \text{g/cm}^3$ and density of wood as $0.4 \ \text{g/cm}^3$)

$A$ solid ball is completely immersed in a liquid. The coefficients of volume expansion of the ball and liquid are $3 \times 10^{-6} / ^\circ C$ and $8 \times 10^{-6} / ^\circ C$ respectively. The percentage change in upthrust when the temperature is increased by $100 ^\circ C$ is ....... $\%$

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