Consider a water tank shown in the figure. It has one wall at $x=L$ and can be taken to be very wide in the $z$ direction. When filled with a liquid of surface tension $S$ and density $\rho$, the liquid surface makes angle $\theta_0\left(\theta_0 \ll 1\right)$ with the $x$-axis at $x=L$. If $y(x)$ is the height of the surface then the equation for $y(x)$ is:

(take $\theta(x)=\sin \theta(x)=\tan \theta(x)=\frac{d y}{d x}, g$ is the acceleration due to gravity)

An ideal fluid is flowing in a non-uniform cross-sectional tube $$X Y$$ (as shown in the figure) from end $$X$$ to end $$Y$$. If $$K_1$$ and $$K_2$$ are the kinetic energy per unit volume of the fluid at $$X$$ and $$Y$$ respectively, then the correct option is :

The maximum elongation of a steel wire of $$1 \mathrm{~m}$$ length if the elastic limit of steel and its Young's modulus, respectively, are $$8 \times 10^8 \mathrm{~N} \mathrm{~m}^{-2}$$ and $$2 \times 10^{11} \mathrm{~N} \mathrm{~m}^{-2}$$, is:

A thin flat circular disc of radius $$4.5 \mathrm{~cm}$$ is placed gently over the surface of water. If surface tension of water is $$0.07 \mathrm{~N} \mathrm{~m}^{-1}$$, then the excess force required to take it away from the surface is