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
$\sqrt{\frac{ P }{2 \rho}+ v ^{2}}$
$\sqrt{\frac{ P }{\rho}+ v ^{2}}$
$\sqrt{\frac{2 P }{\rho}+ v ^{2}}$
$\sqrt{\frac{ P }{\rho}+ v }$
Why is it dangerous to stand on the edge of platform near the line, when the train is passing with speed ? Explain.
An ideal fluid of density $800 \; kgm ^{-3}$, flows smoothly through a bent pipe (as shown in figure) that tapers in cross-sectional area from $a$ to $\frac{ a }{2}$. The pressure difference between the wide and narrow sections of pipe is $4100 \; Pa$. At wider section, the velocity of fluid is $\frac{\sqrt{x}}{6} \; ms ^{-1}$ for $x = \dots$ $\left(\right.$ Given $g =10 \; m ^{-2}$ )
When a fluid passes through a constricted part of a pipe, what happens to its velocity and pressure ?
Force in Column - $\mathrm{I}$ and its use is in Column - $\mathrm{II}$ are given. Match them appropriately.
Column - $\mathrm{I}$ | Column - $\mathrm{II}$ |
$(a)$ Cohesive force | $(i)$ Useful for writing by chalk on blackboard. |
$(b)$ Adhesive force | $(ii)$ Useful in soldering. |
$(iii)$Useful for formation of spherical drops of liquid. |
Why does an airplane run a certain length on the runway first before taking off ?