MECHANICAL PROPERTIES OF FLUIDS

Explain why

(a) The angle of contact of mercury with glass is obtuse, while that of water       with glass is acute.

(b) Water on a clean glass surface tends to spread out while mercury on the

same surface tends to form drops. (Put differently, water wets glass while

mercury does not.)

(c) Surface tension of a liquid is independent of the area of the surface

(d) Water with detergent disolved in it should have small angles of contact.

(e) A drop of liquid under no external forces is always spherical in shape