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# What are Physics Forces?

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• Written By: Daniel Liden
• Edited By: Bronwyn Harris
2003-2018
Conjecture Corporation
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Physics forces are external objects or agents that cause change in the motion of other free objects or stress in fixed objects or bodies. Quite simply, a force applies a push or pull to an object that causes it to change direction, change velocity, or deform to some degree. Physics forces have magnitude and direction, which makes them, for mathematical purposes, vector quantities. There are many different types of forces, from simple physical objects colliding to complex electromagnetic fields repelling various objects. Scientists still do not fully understand the workings of forces, as many, such as gravity, are intrinsically linked to the largely-unknown field of quantum physics.

There are many different physics forces that have been observed and that are used in calculations concerning physics. Applied forces are generally considered to be the simplest of forces. Though most kinds of forces could typically be considered applied forces, the term is usually reserved for actions, often human, that directly push or pull on a system. Another common and important force is known as the normal force. The normal force is the equal force applied by an object, such as the floor, when another object applies pressure to it; this force is the reason people do not sink into the ground when they walk across it.

One of the most important forces is gravity, which was not identified as a force until the work of Isaac Newton. Gravity meets the definition of a force because it causes change in the motion of objects. A ball thrown into the air will, of course, return to the ground because of the force of gravity. Electromagnetic forces are also commonly-studied physics forces involving the pulls and repulsions between differently charged objects.

Nuclear forces are an integral part of the study of physics forces, especially in the area of quantum physics. There are two primary types of nuclear forces, the strong nuclear force and the weak nuclear force. The strong nuclear force is the force that is responsible for holding together the subatomic particles that make up the nucleus of an atom, and the weak atomic force is involved in the decay of subatomic particles.

There are many other kinds of forces as well. All physics forces, however, do essentially the same thing in very different ways and on very different scales. They cause change, usually relating to motion, in other objects. Many physics forces are interrelated and can have varying effects on each other.

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 Fiorite Post 2 @ Alchemy- The four fundamental forces of physics you write about all have associated elementary particles that facilitate these forces except gravity. Photons exert electromagnetic forces, gluons mediate strong nuclear forces, and bosons are the mediators of weak nuclear forces. Physicists predict the existence of a massless particle that acts as a force carrier for gravity. Physicists have named this theoretical particle a graviton, but physicists have not discovered them yet. There are theoretical difficulties in proving the existence of gravitons, mostly having to do with their behavior at energies approaching the Planck scale. If Physicists are successful at discovering the existence of gravitons, then they may be able to create the theory of everything that you speak of in your post. This would allow physicists to combine the theories of general relativity and quantum mechanics. Alchemy Post 1 The four most important forces in physics are gravity, electromagnetism, strong nuclear forces, and weak nuclear forces. These four forces can describe almost any physical phenomenon, and they dictate the physical make-up of our universe. In fact, the multiverse theory, a theory about the existence of multiple universes, is based on the theory of cosmic inflation. The Cosmic inflation theory describes the composition of our universe and the forces driving the big bang. The balance of these four physical forces is what dictates the processes and properties of our universe. In the multiverse theory, the differences in the balance of these four forces would determine the physics of each individual universe in the multiverse. The importance of these four forces in physics cannot be underestimated. Further understanding of these forces, and how they affect particles, could eventually lead to a theory of everything. Physicists could then use this theory of everything to describe all physical phenomenons and predict the outcome of unknown events.