Question

In which of the following phenomena is surface tension important?
the floating of a boat in water
the floating of a steel wire in water
the floating of a ballon in air
the floating of a plastic sphere in water

Answer 1

The surface intention phenomenon is important in case of floating of a steel wipe in water only.

As consequence of Archimedes' principle the steel wipe should sink in water as the density of steel above water density, therefore floats it can only from for surface tension forces.

In all other cases the total density is less than density of water (air in case the floating of a balloon in air) and surface tension force of significant influence does not render.

Condition of floats: $\rho < or = \rho(\text{water or air}), \text{were } \rho = \frac{m}{v}$