A small piece of wire 4 cm long is floating on the surface of water. If a force of 560 dynes in excess of its weight is required to pull it up from the surface, find the surface tension of water.

A small piece of wire 4 cm long is floating on the surface of water. I

1.	A small piece of wire 4 cm long is floating on the surface of water. If a force of 560 dynes in excess of its weight is required to pull it up from the surface, find the surface tension of water.
Answer» Solution :LENGTH of wire `l=4cm` Contact length of solid with liquid surface `L=2l=8cm` Surface tension `S=(F)/(L)impliesS=(560)/(8)=70` dyne/CM Surface tension of water = 70 dyne `cm^(-1)=0.07Nm^(-1)`.