Why does the free surface of a liquid tend to contract?

The rain drops are in spherical shape due to

$A$ straw of circular cross-section of radius $R$ and negligible thickness is dipped vertically into a liquid of surface tension $T$. If the contact angle between the liquid and the straw material is $53^{\circ}$,what is the force acting on the straw due to the surface tension of the liquid? (Given: $\cos 53^{\circ} = 0.6$)

$A$ wire of length $10 \text{ cm}$ is gently placed horizontally on the surface of water having surface tension of $75 \times 10^{-3} \text{ N/m}$. What force is required to just pull up the wire from the water surface?

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 an 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 $\theta(x) \approx \sin \theta(x) \approx \tan \theta(x) = \frac{dy}{dx}$,where $g$ is the acceleration due to gravity.)

Describe a simple experiment for the measurement of the surface tension of a liquid.