A spherical ball of density $\rho$ and radius $0.003$ $m$ is dropped into a tube containing a viscous fluid filled up to the $0$ $ cm$ mark as shown in the figure. Viscosity of the fluid $=$ $1.260$ $N.m^{-2}$ and its density $\rho_L=\rho/2$ $=$ $1260$ $kg.m^{-3}$. Assume the ball reaches a terminal speed by the $10$ $cm$ mark. The time taken by the ball to traverse the distance between the $10$ $cm$ and $20$ $cm$ mark is
( $g$ $ =$ acceleration due to gravity $= 10$ $ ms^{^{-2}} )$
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Air of density $1.2\,kg\,m^{-3}$ is blowing across the horizontal Wings of an aeroplane in such a way that its speeds above and below the wings are $150\,ms^{-1}$ and $100\,ms^{-1}$, respectively. The pressure difference between the upper and lower sides of the Wings, is ........ $Nm^{-2}$
Spherical balls of radius $ 'r'$ are falling in a viscous fluid of viscosity '$\eta$' with a velocity $ 'v'. $ The retarding viscous force acting on the spherical ball is
Two bodies are in equilibrium when suspended in water from the arms of a balance. The mass of one body is $36 g $ and its density is $9 g / cm^3$. If the mass of the other is $48 g$, its density in $g / cm^3$ is
A very large block of ice of the size of a volleyball court and of uniform thickness of $8 \,m$ is floating on water. A person standing near its edge wishes to fetch a bucketful of water using a rope. The smallest length of rope required for this is about ............... $m$
A solid sphere, of radius $R$ acquires a terminal velocity $\nu_1 $ when falling (due to gravity) through a viscous fluid having a coefficient of viscosity $\eta $. The sphere is broken into $27$ identical solid spheres. If each of these spheres acquires a terminal velocity, $\nu_2$, when falling through the same fluid, the ratio $(\nu_1/\nu_2)$ equals
Water enters through end $A$ with speed ${v_1}$ and leaves through end $B$ with speed ${v_2}$ of a cylindrical tube $AB$. The tube is always completely filled with water. In case $I$ tube is horizontal and in case $ II$ it is vertical with end $ A $ upwards and in case $ III $ it is vertical with end $B$ upwards. We have ${v_1} = {v_2}$ for
Water is flowing through a tube of non-uniform cross-section ratio of the radius at entry and exit end of the pipe is $ 3 : 2.$ Then the ratio of velocities at entry and exit of liquid is