  (Abridged) We investigate how galactic disks react to external tidal torques.
We calculate the strength and radial dependence of torques on disks that arise
from a misalignment between the disk and the main axis system of a flattened
dark matter halo. We find that except for in the very inner regions, the
torques are well-described by a power law of the form $\tau \propto r^{-2.5}$.
The magnitude of the torque is large enough for the entire disk to react to the
torque in less than the Hubble time. We demonstrate analytically that disks
which are originally located in the $xy$-plane and which are subjected to a
torque around the x-axis tilt around the y-axis, as also found in fully
non-linear N-body simulations. We further demonstrate that that the torque
causes the radius of a chosen particle to increase with time. Investigations of
tilting disks which treat the disk as a set of solid rings thus may
systematically overestimate the effects of the torque by a factor of two. For
torques of the form we investigate, the inner regions of the disk react to the
torque faster than the outer regions, resulting in a trailing warp. We then
study the effect of the self-gravity of the disk in such a scenario using
numerical N-body models. Self-gravity flattens out the inner regions of the
disk, but these regions are tilted with respect to their initial plane followed
by a non-flat outer region whose tilt decreases with radius. The ``warp
radius,'' which marks the end of the inner flat disk, grows throughout the disk
at a rate that depends only on the strength of the torque and the local surface
density of the disk.
