  A stationary magnetic dipole immersed in an electric field carries "hidden"
mechanical momentum. However, the fate of this momentum if the fields are
turned off is unclear. We consider a charge-and-dipole hidden momentum
configuration, and turn off the fields by collapsing a null shell onto the
system, forming a black hole. In numerical calculations we find that the black
hole receives a kick corresponding to 0.1% of the initial stored momentum. When
extrapolated to apply to purely gravitational phenomena, this efficiency
suggests a role for the hidden momentum kick mechanism in generating the binary
black hole "superkicks" observed in numerical simulations of Einstein's
equation.
