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The Simple Case
Consider a particle moving in a straight line that is acted on by a constant force in the same
direction as the motion of the particle. In this very simple case, the work is defined as the product
of the force and the displacement of the particle. Unlike a situation in which you hold something
in place, exerting a normal force, the crucial aspect to the concept of work is that it defines a
constant force
applied over a distance.
If a force
F
acts on a particle over a distance
x
, then the
work done is simply:
W
=
Fx
Since
w
increases as
x
increases, given a constant force, the greater the distance during which
that force acts on the particle, the more work is done. We can also see from this equation that
work is a
scalar
quantity, rather than a
vector
one. Work is the product of the magnitudes of the
force and the displacement, and direction is not taken into account.
What are the units of work? The work done by moving a 1 kg body a distance of 1 m is defined
as a Joule. A joule, in terms of fundamental units, is easily calculated:
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 Fall '10
 DavidJudd
 Physics, Force, Work

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