A glass prism has its principal section in form of an equilateral triangle of side length `l`. The length of the prism is L (see fig.). The prism, with its base horizontal, is supported by a vertical spring of force constant k. Half the slant surface of the prism is submerged in water. Surface tension of water is T and contact angle between water and glass is `0^(@)`. Density of glass is d and that of water is `rho ( lt d)`. Calculate the extension in the spring in this position of equilibrium.

Answer

`x=1/K[sqrt(3)/4 l^(2)Ld.g-(3sqrt(3))/16 l^(2)Lrhog+sqrt(3) TL+Tl]`