I was solving a problem from fluid mechanics... But that led me to question my conception abt surface tension... The problem stated that the max force needed to uphold a needle(ignore its weight)from the water surface is F... The needle is L m long... What is the surface tension? They found it by T=F/2L I know how surface tension works... But I fail to grasp this problem... Why do we need force at all to take out the needle?