point mass

An example of a point mass graphed on a grid. The grey mass can be simplified to a point mass (the black circle). It becomes practical to represent point mass as small circle, or dot, as an actual point is invisible.

Point mass is an idealistic term used to describe either matter which is infinitely small, or an object which can be thought of as infinitely small. This concept in terms of size is similar to that of point particles, however unlike point particles the object need only be considered infinitely small.

Application

Physics

The concept of point mass has applications in both mathematics and physics. A common use for point mass lays in the consideration of the gravitational force fields. When analyzing the gravitational forces in a system, it becomes impossible to account for every unit of mass individually. When none of the object's circumferences from the center of mass overlap, it becomes possible to think of the center of mass containing all of the mass of the object.

Mathematics

A point mass in statistics is a discontinuous segment in a probability distribution. To calculate such point mass, an integration is carried out over the entire range of the random variable, on the probability distribution of the continuous part. After equating this integral to 1, the point mass can be found by further calculation.

See also

• Point particle
• Point charge
• Pendulum
• Kinematics
• Position vector
• Random variable
• Shell theorem

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