6 Kinds of Simple Machines

6 Kinds of Simple Machines Work is performed by applying a force over a distance. These six simple machines create a greater output force than the input force; the ratio of these forces is the mechanical advantage of the machine. All six of the simple machines listed here have been used for thousands of years, and the physics behind several of them were quantified by the Greek philosopher Archimedes (ca. 287–212Â  BCE). When combined, these machines can be used together to create an even greater mechanical advantage, as in the case of a bicycle. Lever A lever is a simple machine that consists of a rigid object (often a bar of some kind) and a fulcrum (or pivot). Applying a force to one end of the rigid object causes it to pivot about the fulcrum, causing a magnification of the force at another point along the rigid object. There are three classes of levers, depending on where the input force, output force, and fulcrum are in relation to each other. The earliest lever was in use as a balance scale by 5000 BCE; Archimedes is credited with saying Give me a place to stand and I will move the earth. Baseball bats, seesaws, wheelbarrows, and crowbars are all types of levers. Wheel Axle A wheel is a circular device that is attached to a rigid bar in its center. A force applied to the wheel causes the axle to rotate, which can be used to magnify the force (by, for example, having a rope wind around the axle). Alternately, a force applied to provide rotation on the axle translates into rotation of the wheel. It can be viewed as a type of lever that rotates around a center fulcrum. The earliest wheel and axle combination known was a toy model of a four-wheeled cart made in Mesopotamia about 3500 BCE. Ferris wheels, tires, and rolling pins are examples of wheels and axles. Inclined Plane An inclined plane is a plane surface set at an angle to another surface. This results in doing the same amount of work by applying the force over a longer distance. The most basic inclined plane is a ramp; it requires less force to move up a ramp to a higher elevation than to climb to that height vertically. No one invented the inclined plane since it occurs naturally in nature, but people used ramps to build large buildings (monumental architecture) as early as 10,000–8,500Â  BCE. Archimedess On Plane Equilibrium describes the centers of gravity for various geometrical plane figures. Wedge The wedge is often considered a double inclined plane- both sides are inclined- that moves to exert a force along the lengths of the sides. The force is perpendicular to the inclined surfaces, so it pushes two objects (or portions of a single object) apart. Axes, knives, and chisels are all wedges. The common door wedge uses the force on the surfaces to provide friction, rather than separate things, but its still fundamentally a wedge. The wedge is the oldest simple machine, made by our ancestors Homo erectus at least as long ago as 1.2 million years to make stone tools. Screw A screw is a shaft that has an inclined groove along its surface. By rotating the screw (applying a torque), the force is applied perpendicular to the groove, thus translating a rotational force into a linear one. It is frequently used to fasten objects together (as the hardware screw and bolt does). The Babylonians in Mesopotamia developed the screw in the 7th century BCE, to elevate water from a low-lying body to a higher one (irrigate a garden from a river). This machine would later to be known as Archimedes screw. Pulley A pulley is a wheel with a groove along its edge, where a rope or cable can be placed. It uses the principle of applying force over a longer distance, and also the tension in the rope or cable, to reduce the magnitude of the necessary force. Complex systems of pulleys can be used to greatly reduce the force that must be applied initially to move an object. Simple pulleys were used by the Babylonians in the 7th century BCE; the first complex one (with several wheels) was invented by the Greeks about 400 BCE. Archimedes perfected the existing technology, making the first fully-realized block and tackle. Whats a Machine? The first use of the word machine (machina) in Greek was by the ancient Greek poet Homer in the 8th century BCE, who used it to refer to political manipulation. The Greek playwright Aeschylus (523–426 BCE) is credited with using the word in reference to theatrical machines such as the deus ex machina or god from a machine. This machine was a crane that brought actors playing gods onto the stage. Sources and Further Reading Bautista Paz, Emilio, et al. A Brief Illustrated History of Machines and Mechanisms. Dordrecht, Germany: Springer, 2010. Print.Ceccarelli, Marco. Contributions of Archimedes on Mechanics and Design of Mechanisms. Mechanism and Machine Theory 72 (2014): 86–93. Print.Chondros, Thomas G. Archimedes Life Works and Machines. Mechanism and Machine Theory 45.11 (2010): 1766–75. Print.PIsano, Raffaele, and Danilo Capecchi. On Archimedean Roots in Torricellis Mechanics. The Genius of Archimedes: 23 Centuries of Influence on Mathematics, Science, and Engineering. Eds. Paipetis, Stephans A. and Marco Ceccarelli. Proceedings of an International Conference Held at Syracuse, Italy, June 8–10, 2010. Dordrecht, Germany: Springer, 2010. 17–28. Print.Waters, Shaun, and George A. Aggidis. Over 2000 Years in Review: Revival of the Archimedes Screw from Pump to Turbine. Renewable and Sustainable Energy Reviews 51 (2015): 497–505. Print.

10 jobs with the highest divorce rates

10 jobs with the highest divorce rates We work because we have to, and also to make life better- jobs afford us the income we need to survive, in addition to hopefully offering some level of personal fulfillment. Unfortunately, work can also have negative consequences that spill over into our personal lives. One of the worst side effects of a job is when it interferes with marriages, and certain jobs are more likely to lead to divorce than others. The following 10 jobs have the highest divorce rates, and you may be surprised by some of the results. 1. Dancer/ChoreographerBelieve it or not, dancers and dance choreographers are the professionals most at risk for divorce. The intimacy of dancing often leads to extramarital affairs between co-workers.2. BartenderLess of a shock is that fact that a large number of married bartenders split up with their spouses. Just think about it: a workplace in which people gather to hook up + heavy doses of free-flowing alcohol = a recipe for disaster for some people.3. Massage TherapistWha t’s more intimate than swaying together on the dance floor or sharing a shot at the bar? Well, touching another person’s unclothed body comes to mind. That’s the job description of massage therapists, so it is unsurprising that their marriages tend to break up.4. Gaming Cage WorkerBeing a gaming cage worker involves conducting financial transactions at casinos. Casinos attract clientele who enjoy the edgy entertainments of gambling and drinking, and such people may be more likely to engage in the equally risky pursuit of infidelity. Gaming cage workers have the extra enticement of dealing directly with money, which is a major turn on for a lot of people.5. Extruding Machine OperatorsAn extruding machine operator works on an assembly line. One theory is that this repetitious, alienating, and highly unstable work causes a psychological disconnect in workers that can lead to divorce. It is also low-paying work performed by people with relatively little education, w hich can also be factors in unstable marriages.6. Gaming Service WorkerNow we return to the casino for another job that often spells trouble for marriages. Gaming service workers tend to get divorced for the same reasons as gaming cage workers. They are possibly slightly less at risk since gaming service workers are not actually involved in the exchange of money, though there is more direct contact with other people.7. Factory WorkerLike extruding machine operators, factory workers perform repetitive, low-paying work that does not require a higher education degree. Such people are likelier to get divorces than highly educated, financially stable individuals who get to perform more intellectually stimulating and personally fulfilling work.8. Switchboard OperatorSwitchboard operator may seem like a decidedly old-fashioned job, but these folks who direct our phone calls are still around in great enough number to register in divorce-rate censuses. The stress of switchboard work is a maj or factor in the high divorce rate of people who perform this rapidly disappearing job.9. Nurse/Health AideWorking as a nurse or health aide comes with the dual issues of being highly stressful and extremely intimate. The long hours involved in such work can put a major strain on a marriage, and the close contact between worker and patient can lead to infidelity.10. Entertainer/Performer/Pro AthleteYou may have expected entertainers and pro athletes to take the top spot on this list since no one receives more attention for getting divorced than entertainers and athletes. Of course, no one receives more attention for doing absolutely anything than entertainers and pro athletes. Nevertheless, these are jobs that involve spending weeks or months away from home and being on the receiving end of adulation from fans who often have more in mind than snagging an autograph.