In the following movies a layer of grain with a depth
of 9 diameter is vibrated horizontally (see the experimental Device).
The frequency of the oscillation is 3.33 Hz. The frame rate of the
movies is 100fps.
For an acceleration equal to 0.36 g no motion
relative to the container (located by a black marker)can be detected
in the Lab frame (see movie). And indeed
particles are almost at rest in the Box frame (see
For a slightly higher acceleration equal 0.41 g, particles seem
still motionless relative to the container in the Lab frame (see
movie). However a closer look in the Box frame reveals that
particles move during a part a of the excitation cycle
For an acceleration equal to 0.47 g, a well developed motion during
the entire cycle is obvious in both the Lab frame (see
movie) and the Box frame (see movie).