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Laminar flow over a body occurs when layers of the fluid move smoothly past each other in parallel lines. In nature, this kind of flow is rare. As the fluid flows over an object, it applies frictional forces to the surface of the object which works to impede forward movement of the object; the result is called skin friction drag.
Specialized malware designed to attack those systems does exist. However, the vast majority of viruses are developed for Microsoft Windows. [195] The deep web is not primarily full of pornography, illegal drug trade websites, and stolen bank details. This information is primarily found in a small portion of the deep web known as the "dark web ...
Lubricated friction is a case of fluid friction where a lubricant fluid separates two solid surfaces. [9] [10] [11] Skin friction is a component of drag, the force resisting the motion of a fluid across the surface of a body. Internal friction is the force resisting motion between the elements making up a solid material while it undergoes ...
Not all forces are contact forces; for example, the weight of an object is the force between the object and the Earth, even though the two do not need to make contact. Gravitational forces, electrical forces and magnetic forces are body forces and can exist without contact occurring.
Frictionless planes do not exist in the real world. However, if they did, one can be almost certain that objects on them would behave exactly as Galileo predicts. Despite their nonexistence, they have considerable value in the design of engines, motors, roadways, and even tow-truck beds, to name a few examples.
Sunflowers do not always point to the Sun. Flowering sunflowers face a fixed direction (often east) all day long, but do not necessarily face the Sun. However, in an earlier developmental stage, before the appearance of flower heads, the immature buds do track the Sun (a phenomenon called heliotropism). Mature flowers face east.
Apparent competition has also been viewed in and on the human body. The human immune system can acts as the generalist predator, and a high abundance of a certain bacteria may induce an immune response, damaging all pathogens in the body. Another example of this is of two populations of bacteria that can both support a predatory bacteriophage.
A wheeled buffalo figurine—probably a children's toy—from Magna Graecia in archaic Greece [1]. Several organisms are capable of rolling locomotion. However, true wheels and propellers—despite their utility in human vehicles—do not play a significant role in the movement of living things (with the exception of the corkscrew-like flagella of many prokaryotes).