A uniform rod of density $\rho $ is placed in a wide tank containing a liquid of density ${\rho _0}({\rho _0} > \rho )$. The depth of liquid in the tank is half the length of the rod. The rod is in equilibrium, with its lower end resting on the bottom of the tank. In this position the rod makes an angle $\theta $ with the horizontal
a (a)Let $L = PQ =$ length of rod
$SP = SQ = \frac{L}{2}$
Weight of rod, $W = Al\rho g$, acting
At point $S$
And force of buoyancy,
${F_B} = Al{\rho _0}g$, $[l = PR]$
which acts at mid-point of $PR.$
For rotational equilibrium,
$Al{\rho _0}g \times \frac{l}{2}\cos \theta = AL\rho g \times \frac{L}{2}\cos \theta $
==> $\frac{{{l^2}}}{{{L^2}}} = \frac{\rho }{{{\rho _0}}}$ ==> $\frac{l}{L} = \sqrt {\frac{\rho }{{{\rho _0}}}} $
From figure, $\sin \theta = \frac{h}{l} = \frac{L}{{2l}} = \frac{1}{2}\sqrt {\frac{{{\rho _0}}}{\rho }} $
Download our app
and get started for free
Experience the future of education. Simply download our apps or reach out to us for more information. Let's shape the future of learning together!No signup needed.*
An open glass tube is immersed in mercury in such a way that a length of $8\ cm$ extends above the mercury level. The open end of the tube is then closed and sealed and the tube is raised vertically up by additional $46\ cm$. What will be length of the air column above mercury in the tube now ....... $cm$ ?
An open $U$-tube contains mercury. When $13.6 \,cm$ of water is poured into one of the arms of the tube, then the mercury rise in the other arm from its initial level is ....... $cm$
Three identical vessels are filled with equal masses of three different liquids $A, B$ and $C$ $({\rho _A} > {\rho _B} > {\rho _C})$. The pressure at the base will be
Increase in pressure at one point of the enclosed liquid in equilibrium of rest is transmitted equally to all other points of liquid. This is as per ...........
A small hole of area of cross-section $2\; \mathrm{mm}^{2}$ is present near the bottom of a fully filled open tank of height $2\; \mathrm{m} .$ Taking $\mathrm{g}=10 \;\mathrm{m} / \mathrm{s}^{2},$ the rate of flow of water through the open hole would be nearly ......... $\times 10^{-6} \;m^{3} /s$
A small ball of mass $m$ and density $\rho$ is dropped in a viscous liquid of density $\rho_0$. After sometime, the ball falls with constant velocity. The viscous force on the ball is: