Class 11PhysicsMechanical Properties of FluidsBernoulli's Theorem and Applications of Bernoulli's Theory
MediumWhy is it dangerous to stand on the edge of a platform near the tracks when a train is passing at high speed? Explain.
(N/A) When a train passes at high speed,the air in contact with the train moves with the same velocity as the train. According to Bernoulli's principle,as the velocity of the air increases,its pressure decreases. This creates a region of low pressure between the person and the train. Since the air pressure further away from the train remains higher,a net pressure difference is created. This pressure difference exerts a force on the person directed towards the train,which can pull the person towards the moving train,making it dangerous.
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Similar Questions
Determine the pressure difference in a tube of non-uniform cross-sectional area as shown in the figure. $\Delta P = ?$ (in $Pa$)
$d_{1} = 5 \, cm, V_{1} = 4 \, m/s, d_{2} = 2 \, cm, V_{2} = ?$
Assume the fluid is water with density $\rho = 1000 \, kg/m^{3}$.
$d_{1} = 5 \, cm, V_{1} = 4 \, m/s, d_{2} = 2 \, cm, V_{2} = ?$
Assume the fluid is water with density $\rho = 1000 \, kg/m^{3}$.
MediumAIIMS 2019
View SolutionAn ideal fluid of density $800 \; kg \cdot m^{-3}$ flows smoothly through a bent pipe (as shown in the figure) that tapers in cross-sectional area from $a$ to $\frac{a}{2}$. The pressure difference between the wide and narrow sections of the pipe is $4100 \; Pa$. At the wider section,the velocity of the fluid is $\frac{\sqrt{x}}{6} \; m \cdot s^{-1}$. Find the value of $x$. (Given $g = 10 \; m \cdot s^{-2}$)
DifficultJEE MAIN 2022
View SolutionWater (of density $\varrho$) flows steadily through a horizontal pipe of variable cross-section. If the pressure of water is $P$ at a point where the flow speed is $V$,then the pressure at another point where the flow speed becomes $3V$ is:
Different heads are in Column - $I$ and their formulas are given in Column - $II$. Match them appropriately.
Column - $I$ Column - $II$ $(a)$ Velocity head $(i)$ $\frac{P}{\rho g}$ $(b)$ Pressure head $(ii)$ $h$ $(c)$ Potential head $(iii)$ $\frac{v^2}{2g}$
| Column - $I$ | Column - $II$ |
| $(a)$ Velocity head | $(i)$ $\frac{P}{\rho g}$ |
| $(b)$ Pressure head | $(ii)$ $h$ |
| $(c)$ Potential head | $(iii)$ $\frac{v^2}{2g}$ |
Easy
View Solution$A$ tank of height $15 \ m$ and cross-section area $10 \ m^2$ is filled with water. There is a small hole of cross-section area $a$ which is much smaller than the container, located at a height of $12 \ m$ from the base of the container. How much force should be applied with a piston at the top level, so that the water coming out of the hole hits the ground at a distance of $16 \ m$ (in $kN$)? (Take, density of water $\rho = 1000 \ kg \ m^{-3}$ and $g = 10 \ m/s^2$)
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