Floating Needle. A needle $($specific weight $g$ and length $L)$ can float on a water surface, because the surface tension $["$force per unit length"$]$ of the water can lead to forces strong enough to support the needle's weight. Develop a set of pi terms for the above situation in terms of variables

$(,g,,L)$

Ans. One $$:${}_1=g\frac{L^2}{}=Bo($Bond number; gravity$-$to$-$surface tension force ratio$)=$ constant.