The document discusses conservative and non-conservative force fields. It states that a force field is conservative if its curl is zero everywhere, meaning the gradient of a scalar potential field can represent it. Option (a) represents a conservative field, while option (b) is not conservative because its curl is non-zero. Option (c) also represents a conservative field because its curl is equal to zero.
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Fowles Cassiday 4.2.doc
1. 1
2
3
, det min
:
(a)
(b) -
(c)
By finding the curl er e
which of the following forces
are conservative
ix jy kz
iy jx kz
iy jx kz
F
F
F
Solution
Conservative Field
In summary, the curl of a conservative force
field is zero everywhere because a field being
conservative is equivalent to having zero curl,
which can be derived in any basic text on
vector analysis. Additionally, a conservative
force field can be written as the gradient of a
scalar field.
2. 2
2 3
4
( )
( 1) 0 ( 1) 0
( 1) 0 0
Conservative
a
i j k
X
x y z
x y z
i X j X
k X
F
3. 3
2
2 3
4
( )
( 1) 0 ( 1) 0
( 1) ( 1 1) 2 0
Not Conservative
b
i j k
X
x y z
y x z
i X j X
k X
F
3
2 3
4
( )
( 1) 0 ( 1) 0
( 1) (1 1) 0
Conservative
c
i j k
X
x y z
y x z
i X j X
k X
F
Analytical Mechanics Grant R. Fowles George L. Cassiday