A body of density $\rho$ is dropped from rest from a height $h$ into a lake of density $\sigma$, where $\sigma > \rho$. Neglecting all dissipative forces, the maximum depth to which the body sinks before returning to float on surface ..........
$\frac{h}{\sigma-\rho}$
$\frac{h \rho}{\sigma}$
$\frac{h \rho}{\sigma-\rho}$
$\frac{h \sigma}{\sigma-\rho}$
If water is flowing in a pipe with speed $2 \,m / s$ then its kinetic energy per unit volume is ........... $J ^2 m ^3$
Bernoulli's principle does not explain
To get the maximum flight, a ball must be thrown as
A fluid is flowing through a horizontal pipe of varying cross-section, with speed $v\;ms^{-1}$ at a point where the pressure is $P$ Pascal. At another point where pressure is $\frac{ P }{2}$ Pascal its speed is $V\;ms^{-1}$. If the density of the fluid is $\rho\, kg\, m ^{-3}$ and the flow is streamline, then $V$ is equal to
A plane is in level flight at constant speed and each of its two wings has an area of $40 \mathrm{~m}^2$. If the speed of the air is $180 \mathrm{~km} / \mathrm{h}$ over the lower wing surface and $252 \mathrm{~km} / \mathrm{h}$ over the upper wing surface, the mass of the plane is______ $\mathrm{kg}$. (Take air density to be $1 \mathrm{~kg} \mathrm{~m}^{-3}$ and $\mathrm{g}=10 \mathrm{~ms}^{-2}$ )