write a short note (including example and diagram) (130 - 150 words)on :- a. surface tension b. viscosity
Answers
REAL LIFE EXAMPLES OF VISCOSITY - EXAMPLE
1) Consider two cases. The first one is water is poured into a beaker and the second one is honey poured into a beaker.
We can see that water flows faster than honey. This is because honey is more viscous than water.
2) Consider a river flowing. The water near the ground seems steady. On the other hand the water at the top moves faster. This is due to visous forces on different layers of the water.
CAUSE OF SURFACE TENSION - DEFINITION
An unbalanced cohesive force experienced by molecules on the surface of the liquid is responsible for the surface tension.
SOME APPLICATIONS OF SURFACE TENSION - DEFINITION
Some applications of surface tension
Surface tension of soap solution is less, it can spread over large areas and wash clothes more effectively, since the dirt particles stick to the soap molecules.
In soldering, addition of flux reduces the surface tension of molten tin. Hence, it spreads.
Antiseptics like dettol have low surface tension, so that they spread faster.
Surface tension prevents water from passing through the pores of an umbrella.
A duck is able to float on water as its feathers secrete oil that lowers the surface tension of water.
Answer:
normal force acting per unit area on surface of water called surface tension