  We consider the collision of a dark soliton with an obstacle in a
quasi-one-dimensional Bose condensate. We show that in many respects the
soliton behaves as an effective classical particle of mass twice the mass of a
bare particle, evolving in an effective potential which is a convolution of the
actual potential describing the obstacle. Radiative effects beyond this
approximation are also taken into account. The emitted waves are shown to form
two counterpropagating wave packets, both moving at the speed of sound. We
determine, at leading order, the total amount of radiation emitted during the
collision and compute the acceleration of the soliton due to the collisional
process. It is found that the radiative process is quenched when the velocity
of the soliton reaches the velocity of sound in the system.
