**X1-121 (2017/01/27)**

**
The paradox of the drift velocity in matter
**

In a simplified approach to a model of the motion of particles in matter under the influence of an external force, the drift velocity is obtained to be half the product of the acceleration due to the external force and the mean time of the free motion. A more accurate analysis of the problem shows that the drift velocity is the product of the acceleration due to the external force and the mean time of the free motion, without that one second coefficient. This more accurate analysis in presented using two methods.