Engineers and scientists use scientific knowledge to design and build machines that make our lives easier. The machines they build today started off with the basics, which are known as Simple Machines. Simple Machines are defined as the simplest mechanisms that use mechanical advantage to multiply force. These machines have either few or no moving parts, and use energy to work. This term is usually referred to the six classical simple machines; lever, wheel and axle, pulley, inclined plane, a wedge and a screw. They make work easier for us by allowing us to push or pull over increased distances, and each have had an enormous impact the course of human civilization. Simple machines are the elementary basics of all complicated machines. For example, wheels, levers, and pulleys are all used in the mechanism of a bicycle.
Things as simple as a knife can also be classified as a simple machine, specifically, a wedge. A knife is a cutting tool, composed of a blade and a handle. A wedge is basically an inclined plane, that can be used to penetrate or split objects, or to stop them from moving, and reduces the force needed to cut through those objects. When the knife is used for food preparation, the main uses are slicing (which involves cutting, by drawing the blade across the food, applying light pressure). Since the knife was among mankind's earliest inventions, the answers to who invented it, and what time it may have been invented may not be accurate, and varies among different sources. However, it is believed that it was first used by the cavemen during prehistoric times, who made crude knives from pieces of obsidian.
The knife can be used in many different ways, mostly depending on the type of knife that is being used, whether the knife is being used as a weapon, as utensils, as tools, or as a traditional or religious implement. The tool itself does nothing, but in the hand of the user it transmits the pressure of the hand and the arm....
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