Water is pumped through the hose shown below, from a lower level to an upper level. Compared to the water at point $1$ , the water at point $2$ 

A $U-$ tube in which the cross-sectional area of the limb on the left is one quarter, the limb on the right contains mercury (density $13.6\ g/cm^3$). The level of mercury in the narrow limb is at a distance of $36\ cm$ from the upper end of the tube. What will be the rise in the level of mercury in the right limb if the left limb is filled to the top with water ....... $cm$

Air is blowing across the horizontal wings of an aeroplane is such a way that its speeds below and above wings are $90\, m/s$ and $120\, m/s$ respectively. If density of air is $1.3\, kg/m^3$, then the pressure difference between lower and upper sides of wings will be ........ $N/m^2$

A tank is filled upto a height $h$ with a liquid and is placed on a platform of height $h$ from the ground. To get maximum range $x_m$ a small hole is punched at a distance of $y$ from the free surface of the liquid. Then

A lead shot of $1\, mm$ diameter falls through a long column of glycerine. The variation of its velocity $v$ with distance covered is represented by

A square hole of side length $l$ is made at a depth of $h$ and a circular hole of radius $r$ is made at a depth of $4\,h$ from the surface of water in a water tank kept on a horizontal surface. If $l << h,\,r << h$ and the rate of water flow from the holes is the same, then $r$ is equal to