A submarine uses much less fuel when traveling on the surface of calm water than when fully submerged, for the same speed.Kaustubh sri said:
Kaustubh sri said:
Water offers less friction than what?Kaustubh sri said:
Kaustubh sri said:
Kaustubh sri said:
AlephZero said:If you are swimming at the surface, you generate waves. Ignoring the "splashing" effect of arms or legs entering or leaving the water, there is a large increase in the resistance force when an object reaches a critical speed which depends mainly on its length, because it is effectively traveling "uphill" trying to climb up the bow wave it generates in front of it. A boat with a high power engine, or a sailing boat in a strong wind, can get "on top of" its bow wave and is then effectively traveling down hill with the front of the hull completely out of the water, until it has to slow down.
Apparently ducklings can do this to escape from predators quickly, even if human swimmers can't. http://jeb.biologists.org/content/198/7/1567.full.pdf
If I were grading this question, you'd get a 0 for that answer. You're essentially saying "water has less friction [than air] because it has less friction than air." It's not an explanation; you're just repeating the question as the answer.Kaustubh sri said:
vela said:
Water offers less friction due to its unique molecular structure. Water molecules are polar, meaning they have a positive and negative end, and this polarity allows them to attract and interact with other molecules, including themselves. When an object moves through water, the water molecules are able to move and reorient themselves around the object, reducing the amount of friction between the object and the water.
Viscosity is the measure of a fluid's resistance to flow, and water has a relatively low viscosity compared to other liquids. This low viscosity means that water molecules can easily move past each other, resulting in less resistance when an object moves through water. This results in less friction compared to more viscous liquids, such as oil.
Water is considered a lubricant because it can reduce the amount of friction between two surfaces. As mentioned before, water molecules are able to move and reorient themselves around an object, creating a layer of lubrication between the object and the surface it is moving against. This reduces the coefficient of friction and makes it easier for the object to move.
Yes, the temperature of water can affect friction. Warmer water has a lower surface tension, which means that the water molecules are able to move more freely and can reduce the amount of friction between an object and the water. Colder water has a higher surface tension, making it more difficult for the water molecules to move and resulting in more friction.
The shape of an object can greatly affect the amount of friction it experiences in water. Objects with streamlined shapes, such as boats, experience less friction because the water molecules can easily flow around them. On the other hand, objects with irregular shapes or rough surfaces will experience more friction as the water molecules get caught on the rough edges, creating more resistance. This is why it is important for ships and boats to have streamlined designs to reduce friction and increase efficiency in water.