Physics

Friction

CONCEPT Friction is the force that resists motion when the surface of one object comes into contact with the surface of another. In a machine, friction reduces the mechanical advantage, or the ratio of output to input: an automobile, for instance, uses one-quarter of its energy on reducing friction. Yet, it is also friction in […]

Centripetal Force

CONCEPT Most people have heard of centripetal and centrifugal force. Though it may be somewhat difficult to keep track of which is which, chances are anyone who has heard of the two concepts remembers that one is the tendency of objects in rotation to move inward, and the other is the tendency of rotating objects […]

Momentum

CONCEPT The faster an object is moving—whether it be a baseball, an automobile, or a particle of matter— the harder it is to stop. This is a reflection of momentum, or specifically, linear momentum, which is equal to mass multiplied by velocity. Like other aspects of matter and motion, momentum is conserved, meaning that when […]

KINEMATICS AND PARTICLE DYNAMICS

Conservation Laws

CONCEPT The term “conservation laws” might sound at first like a body of legal statutes geared toward protecting the environment. In physics, however, the term refers to a set of principles describing certain aspects of the physical universe that are preserved throughout any number of reactions and interactions. Among the properties conserved are energy, linear […]

Density and Volume

CONCEPT Density and volume are simple topics, yet in order to work within any of the hard sciences, it is essential to understand these two types of measurement, as well as the fundamental quantity involved in conversions between them—mass. Measuring density makes it possible to distinguish between real gold and fake gold, and may also […]

Kinematics and Dynamics

CONCEPT Webster’s defines physics as “a science that deals with matter and energy and their interactions.” Alternatively, physics can be described as the study of matter and motion, or of matter in motion. Whatever the particulars of the definition, physics is among the most fundamental of disciplines, and hence, the rudiments of physics are among […]

FRAME OF REFERENCE

CONCEPT Among the many specific concepts the student of physics must learn, perhaps none is so deceptively simple as frame of reference. On the surface, it seems obvious that in order to make observations, one must do so from a certain point in space and time. Yet, when the implications of this idea are explored, […]

GENERAL CONCEPTS

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