A .......... $m/s$ speed the velocity head of water is equal to pressure head of $40\, cm$ of $Hg$ .

In a $U-$ tube experiment, a column $AB$ of water is balanced by a column $‘CD’$ of oil, as shown in the figure. Then the relative density of oil is

A pan balance has a container of water with an overflow spout on the right-hand pan as shown. It is full of water right up to the overflow spout. A container on the left-hand pan is positioned to catch any water that overflows. The entire apparatus is adjusted so that it’s balanced. A brass weight on the end of a string is then lowered into the water, but not allowed to rest on the bottom of the container. What happens next?

A boat carrying a number of stones is floating in a water tank. If the stones are unloaded into water, the water level in the tank will ............

The diagram (figure) shows a venturimeter, through which water is flowing. The speed of water at $X$ is $2\,cm/s$. The speed of water at $Y$ (taking $g = 1000\,cm/s^2$ ) is ........ $cm/s$

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