  The balance of pseudomomentum is discussed and applied to simple elasticity,
ideal fluids, and the mechanics of inextensible rods and sheets. A general
framework is presented in which the simultaneous variation of an action with
respect to position, time, and material labels yields bulk balance laws and
jump conditions for momentum, energy, and pseudomomentum. The example of simple
elasticity of space-filling solids is treated at length. The pseudomomentum
balance in ideal fluids is shown to imply conservation of vorticity,
circulation, and helicity, and a mathematical similarity is noted between the
evaluation of circulation along a material loop and the J-integral of fracture
mechanics. Integration of the pseudomomentum balance, making use of a
prescription for singular sources derived by analogy with the continuous form
of the balance, directly provides the propulsive force driving passive
reconfiguration or locomotion of confined, inhomogeneous elastic rods. The
conserved angular momentum and pseudomomentum are identified in the
classification of conical sheets with rotational inertia or bending energy.
