![]() ![]() In contrast, 10 Newton, downward is a complete description of the force acting upon an object both the magnitude (10 Newton) and the direction (downward) are given.īecause a force is a vector that has a direction, it is common to represent forces using diagrams in which a force is represented by an arrow. Thus, 10 Newton is not a full description of the force acting upon an object. To fully describe the force acting upon an object, you must describe both the magnitude (size or numerical value) and the direction. As learned in an earlier unit, a vector quantity is a quantity that has both magnitude and direction. Thus, the following unit equivalency can be stated: 1 Newton = 1 kg Ī force is a vector quantity. One Newton is the amount of force required to give a 1-kg mass an acceleration of 1 m/s/s. A Newton is abbreviated by an "N." To say "10.0 N" means 10.0 Newton of force. Contact Forcesįorce is a quantity that is measured using the standard metric unit known as the Newton. ![]() These specific forces will be discussed in more detail later in Lesson 2 as well as in other lessons.Įxamples of contact and action-at-distance forces are listed in the table below. For example, two magnets can exert a magnetic pull on each other even when separated by a distance of a few centimeters. And magnetic forces are action-at-a-distance forces. For example, the protons in the nucleus of an atom and the electrons outside the nucleus experience an electrical pull towards each other despite their small spatial separation. Electric forces are action-at-a-distance forces. Even when your feet leave the earth and you are no longer in physical contact with the earth, there is a gravitational pull between you and the Earth. For example, the sun and planets exert a gravitational pull on each other despite their large spatial separation. Examples of action-at-a-distance forces include gravitational forces. These specific forces will be discussed in more detail later in Lesson 2 as well as in other lessons.Īction-at-a-distance forces are those types of forces that result even when the two interacting objects are not in physical contact with each other, yet are able to exert a push or pull despite their physical separation. Examples of contact forces include frictional forces, tensional forces, normal forces, air resistance forces, and applied forces. forces resulting from action-at-a-distanceĬontact forces are those types of forces that result when the two interacting objects are perceived to be physically contacting each other.Forces only exist as a result of an interaction.Ĭontact versus Action-at-a-Distance Forcesįor simplicity sake, all forces (interactions) between objects can be placed into two broad categories: When the interaction ceases, the two objects no longer experience the force. ![]() Whenever there is an interaction between two objects, there is a force upon each of the objects. Today we have separated these cleanly into forces, momenta, accelerations, inertia, kinetic energy, potential energy, etc.A force is a push or pull upon an object resulting from the object's interaction with another object. As a side note, the development of mechanics was muddled at first because people used the word "force" and similar words for a whole variety of related concepts without appreciating the differences. It all depends on where you take your starting place to be. ![]() If you look at the units of force $\mathrm$, and this would serve as a definition of the kilogram. Remember that momentum is a vector and a change in a vector can involve a change in magnitude, a change in direction, or both (any arbitrary change in a vector can be decomposed into a change in magnitude parallel or antiparallel to the vector and a change in direction perpendicular to the vector). If a force acts on that particle, its momentum will change. It moves through space with constant momentum. There's indeed an underlying intuition with units. This is precisely the type of question I've started asking my introductory students. ![]()
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