A jet of water with cross section of $6$ $cm^2$ strikes a wall at an angle of $60^o $ to the normal and rebounds elastically from the wall without losing energy. If the velocity of the water in the jet is $12$ $m/s$, the force acting on the wall is ....... $N$
$0.864$
$86.4 $
$72 $
$7.2$
The density of the atmosphere is $1.29\, kg/m^3$, then how high would the atmosphere extend ? $(g = 9.81\, m/sec^2)$ ........ $km$
There is a circular tube in a vertical plane. Two liquids which do not mix and of densities $d_1$ and $d_2$ are filled in the tube. Each liquid subtends $90^o$ angle at centre. Radius joining their interface makes an angle $\alpha$ with vertical. Ratio $\frac{{{d_1}}}{{{d_2}}}$ is
Mention two instruments which measure the atmospheric pressure.
Who devised for first time, a method for measuring atmospheric pressure ?
Radius of an air bubble at the bottom of the lake is $r$ and it becomes $ 2r $ when the air bubbles rises to the top surface of the lake. If $P $ $cm$ of water be the atmospheric pressure, then the depth of the lake is