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In many problems
throughout this class,

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we will find it
useful to consider

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how the mass of an
object is distributed

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throughout the object.

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To do this, we will define
a small piece of that object

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and then consider the
mass that's contained

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within that small piece.

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For an object in one dimension,
the differential element

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of length is delta l.

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And that length contains
a certain amount

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of mass, delta m.

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We could also have
a linear object

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in the shape of an arc or
just an arbitrary path.

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For an object in
two dimensions, we

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have an area element, delta A,
that contains a mass delta m.

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For our volume, we have a
volume element, delta V,

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which contains a
certain amount of mass.

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In this case, we can write
the volume element delta

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V as the area A
times this delta x.