ApplicationsofForce - Applications of Force

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Applications of Force We are now ready to look at some applications of Newton's laws. There are three types of forces that we will deal with in this course. The first is applied forces. The other two are natural forces and contact forces. Applied Forces Applied forces are those that arise due to the interaction of the object with some other object. Usually the two objects are in contact for a brief period. An example of this type of force is the force exerted by a person pulling a block or the tension in a line. These forces always depend on the situation being examined. Natural Forces Natural forces are those that arise from fundamental interactions in nature. In reality, both direct action forces and contact forces are applications of natural forces. There are four known natural forces. From our knowledge of particle physics we know that all of the natural forces can be characterized as a force field times a charge. Each charge is associated with a particle. The first of the natural forces to be studied was the gravitational force . This is the force that attracts to bodies together. It creates weight and keeps the planets in orbit around the sun. It has an infinite range. The equivalent charge is the mass of the body, and the associated particle is called the graviton. It is the only one we will look at this semester. The second force that was known classically is the electromagnetic force . This is more commonly recognized as electric forces and magnetic forces. As with gravity, it has infinite range. The charge is the electric charge, and the associated particle is the photon. It is studied in the second semester of this course. The third force is the strong nuclear force . This is the force that holds an atomic nucleus together. It has a limited range (roughly the diameter of a nucleus). The charge is the strong nuclear charge, or color charge, and the associated particles are called gluons. The last known natural force this the weak nuclear force . This is another short ranged nuclear force. It is responsible for the decays of certain particles. The charge is the weak nuclear charge, or hypercharge, and the associated particles are called the gauge bosons. Since the early 1970's there has been considerable effort to unify these four forces into a single theory that describes the forces as a single force. To date, only the electromagnetic and weak forces have been unified, although there are various theories, called grand unified theories , that unite electromagnetic, strong and weak forces. Attempts to unify these with gravity are found in the various superstring theories , or the theories of everything , that are being postulated.
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Contact Forces The last class of forces we will deal with are the contact forces . These forces arose due to the contact of one object with another. They can be
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ApplicationsofForce - Applications of Force

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