Impact of spinning spheres
These videos show an impact of a billiard ball that is not spinning. The billiard ball has markings on it for image detection. It is falling at about 1.7 m/s. The top images are viewed directly from above.
The left hand image has been cleaned very carefully.
The right hand image has been coated with a hydrophobic surface treatment.
Notice how much different the impacts are. Just by changing the surface treatment we can make a cavity!
These billiard balls are also falling at about 1.7 m/s. They are cleaned and coated similar to those above, however, they are spinning with about 100 rad/s.
The left image is starting to cause a large splash and a little bit of air entrainment on the left hand side of the images. The right hand image creates a cavity as above, but it now has a distinct cardioid shape (above) and appears to have a diminished splash formation on the right hand side.
