Point mass

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A point mass in physics is an idealization of a body whose dimensions are very small compared to the other distances which are relevant to the problem. In such cases, the internal structure of the body can be neglected, and the body can be treated as if its mass were concentrated at one point in space (see Newton's sphere theorem).

In some situations, the body can be treated as a point mass for some purposes even if its dimensions are not negligibly small. For example, the gravitational field outside a spherically-symmetric body is the same as if the body were a point mass positioned at the center (with the same total mass, acting as a point source of gravitation).

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.