Originally Posted by sureshs
How far does the ball slide on the strings?
We are really confused about this in the Instruction forum. I see numbers like 1/4 inch, 3.5 cm, several inches, etc. and Wilson shows big string displacement in its videos.
Second question: what is the relation between ball slide distance and string displacement.
What is the effect of string type and tension on these numbers?
Off the top of my head, I've seen sliding from 5 mm to 30-35 mm. It depends on the speed, angle, spin, pattern, COF, and impact location. It also depends on whether the racquet is hand-held or clamped. That is why you see different results from different tests. I do see bigger displacements with stings that slide.
As to time on strings, that too depends. 5 ms is a good average. It can be as long as 7 ms in the throat and as short as 4 ms at the tip. Again, it will depend on effective mass at the hitting point as well as string stiffness at that location (clamped racquets essentially have "infinite" effective mass). But in general, 5 ms is a very good approximation.