# Fluid Mechanics - Short Question Answers 2 | Physics Grade 11 Solution

### Fluid Mechanics

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#### Kinematics

Introduction to Kinematics

# Fluid Mechanics - Short Question Answers 2

1. Why does hot soup taste better than cold soup?
The taste of the soup is based on how well it spreads over the taste buds of the tongue. Since the surface tension is high when the temperature is low, it is unable to spread through the taste buds of the tongue, but when the temperature is high, i.e. hot soup, the surface of water molecules is low due to which the soup spreads all over the taste buds of the tongue and makes the taste good and complete.

2. Antiseptics used in cuts and wounds of human flesh have low surface tension, Why?
If the antiseptics used for cut and wounds in human flesh have low surface tension, they reach to each and every parts of wounds and make relief from pain as well as cure fast.

3. What are cohesive and adhesive forces?
The force of attraction between the molecules of the same substance is called the force of cohesion or cohesive force. It is maximum in solids, lesser in liquids, and the least in gases.
The force attraction between the molecules of the different substances is called Adhesive forces. For example, gum has a greater adhesive force for a solid surface than water.

4. Why mercury does not wet the glass tube?
The angle of contact for mercury in a glass tube is greater than 90 degree. Also, the force of cohesion between the molecules of mercury is greater than the force of adhesion between the mercury and the glass.

5. We use towels to dry our body after taking a shower, why?
Towel consists of a large number of pores, which acts as the capillary tubes. When the towel is pressed against a wet body, the water is absorbed from the wet body into fibers of the towel by the action of capillarity. That’s why towels are used to dry our body after taking a shower.

6. A tiny liquid drop is spherical in shape but a larger drop is oval in shape, why?
The shape of liquid drop depends upon the surface tension and the force of gravity acting on it. The surface tension depends upon the surface area of the drop whereas the force of gravity depends upon the volume of the drop. Therefore, the ratio of surface tension to a force of gravity is inversely proportional to the radius of the drop. When the radius of the drop is small the surface tension dominates the force of gravity and when the radius of the drop is large, the force of gravity dominates the surface tension due to which the tiny liquid drop is spherical in shape but a larger drop is oval in shape.

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