Measurement of Friction Coefficient on a Powder Layer and Fluid Dynamic Study

Results of comparison experiments ~ The basal surface of the disk (1)

The disk having a smooth metal surface as the base was used in order to examine the influence of the basal surface of the disk on friction coefficient.

On a flour layer, the disk stopped suddenly and a total length of the slide was very short (Movie 7). 

The velocity of the disk decreased exponentially (Fig. 18) instead of decelerating in steps as described in the section of major results 2.

m* ranges from 1.24 to 1.53. It was larger than  values obtained for slide runs without the powder layer.
Movie 7.  Sliding of the disk having a smooth metal surface as the base.

Fig. 18. The velocity of the disk versus time elapsed since disk was shot.
Measurement of Friction Coefficient on a Powder Layer and Fluid Dynamic Study