Question

List out the instances in which we make use the floating property of substances in water.​

Answer 1

Answer:

Examples of surface tension:

1. A cargo ship travelling in sea

2. Walking on water: Small insects such as the water strider can walk on water because their weight is not enough to penetrate the surface.

3.Floating a needle: A carefully placed small needle can be made to float on the surface of water even though it is several times as dense as water. If the surface is agitated to break up the surface tension, then needle will quickly sink.

4.Don't touch the tent!: Common tent materials are somewhat rainproof in that the surface tension of water will bridge the pores in the finely woven material. But if you touch the tent material with your finger, you break the surface tension and the rain will drip through.

5.Clinical test for jaundice: Normal urine has a surface tension of about 66 dynes/centimeter but if bile is present (a test for jaundice), it drops to about 55. In the Hay test, powdered sulfur is sprinkled on the urine surface. It will float on normal urine, but will sink if the surface tension is lowered by the bile.

6.Surface tension disinfectants: Disinfectants are usually solutions of low surface tension. This allow them to spread out on the cell walls of bacteria and disrupt them.

7.Soaps and detergents: These help the cleaning of clothes by lowering the surface tension of the water so that it more readily soaks into pores and soiled areas.

8.Washing with cold water: The major reason for using hot water for washing is that its surface tension is lower and it is a better wetting agent. But if the detergent lowers the surface tension, the heating may be unnecessary.

9.Why bubbles are round: The surface tension of water provides the necessary wall tension for the formation of bubbles with water. The tendency to minimize that wall tension pulls the bubbles into spherical shapes.

10.Surface tension and droplets: Surface tension is responsible for the shape of liquid droplets. Although easily deformed, droplets of water tend to be pulled into a spherical shape by the cohesive forces of the surface layer.

Answer 2

Things that are made entirely of substances that are less dense than water are always floating. For example, anything made of Styrofoam or most types of wood or ice.

Explanation:

• A waterproof, gas- or liquid-filled compartment will always float if the total weight of the object is less than the weight of the same amount of water. For example, a soccer ball (filled with air) or a metal can of gasoline (less dense than water).
• Also, any combination of objects to which this applies, for example, a tennis ball with coins attached. The object can tip over, but it's still floating. The new small boats are designed to never sink (unless there is a severe overload).
• When properly constructed, something like a steel boat floats. If the center of gravity is below the center of buoyancy (the center of the mass of water pushed away by the object),  the object is stable, will not tip over when tilted, and will return to its starting position.
• In this case, if the total weight of the object is less than the weight of the same amount of water, then a wave or moving load (eg, the side of a small boat).