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### Volume vs. Capacity

```Date: 05/01/2002 at 18:55:51
From: Lydia Saxton
Subject: Volume vs. Capacity

Can you explain the difference between the terms "volume" and
"capacity"? Most sources I've researched seem to lean toward reserving
the use of the term "volume" for solids (measured in cubic units) and
the term "capacity" for liquids. Is this accurate?

Also, can you define the distinction between "weight" and "mass"? Many
texts use these terms interchangeably. I know that weight is a
function of gravity and mass has to do with atomic structure, which is
not affected by gravity.

A Math Coach for the Los Angeles Unified School District.
```

```
Date: 05/01/2002 at 23:01:11
From: Doctor Peterson
Subject: Re: Volume vs. Capacity

Hi, Lydia.

I would say that volume refers to the space taken up by an object
itself, while capacity refers to the amount of a liquid or other
pourable substance a container can (or does) hold. That more or
less parallels what you have seen. I have never, however, seen both
terms used of the same object without clarification; you wouldn't
talk of the volume of a pitcher, meaning the amount of plastic it is
made of, without carefully saying so, since it is so common to use
the two terms interchangeably. My dictionary gives "capacity" as a
synonymous definition of "volume," though the current edition has
backed away from that somewhat; here's the online version:

http://m-w.com/

volume

3 : the amount of space occupied by a three-dimensional object
as measured in cubic units (as quarts or liters) : cubic capacity

capacity

2 a : the potential or suitability for holding, storing, or
accommodating b : the maximum amount or number that can be
contained or accommodated <a jug with a one-gallon capacity>
<the auditorium was filled to capacity>

In the dictionary's tables of units, as usual, "capacity" is used as
the heading for "liquid measure" (gallons, etc.) and "dry measure"
(bushels, etc.), and "volume" for cubic units. The former are used,
as I suggested, to measure "pourable" substances, the latter for
anything (since you can convert gallons to cubic feet to see how much
space it takes up).

But while I would use the term "capacity" to describe the unit, I
would not speak of the number of gallons of milk as the "capacity of
the milk," but as its volume - since, as I said, "volume" refers to
the amount of a substance itself, and the milk is not a container. So
really, capacity applies not to the liquids, but to containers. It's
the "units of capacity" that are used for liquids.

As for mass and weight, this should cover it:

Mass vs. Weight
http://mathforum.org/library/drmath/view/56250.html

Mass vs. Weight
http://mathforum.org/library/drmath/view/56320.html

Mass versus Weight
http://mathforum.org/library/drmath/view/56334.html

- Doctor Peterson, The Math Forum
http://mathforum.org/dr.math/
```
Associated Topics:
High School Definitions
High School Higher-Dimensional Geometry
Middle School Definitions
Middle School Higher-Dimensional Geometry

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