Forthcoming Attractions

Rowden — Sun, 01 Jun 2008 16:39:59 +0000

I hope to be including on the site some rather advanced articles for those of you who really need to research all the mathematics and higher science etc. These will be by the ‘Professor’ as we shall call him for the moment, real identity to follow in due course. I append below a little something to whet the appetite.

Aerodynamic Trajectory & Bounce Simulation of a Spinning Table Tennis Ball

Trajectory Model

The trajectories of real bodies moving through the atmosphere are more complicated than the simple

cases presented in texts for non-spinning point-masses projected en-vacuo. Table tennis balls

display fascinating motions through air due to the high speeds and spins coupled with their light

mass. Aerodynamic forces create non-planar flight trajectories and the equations that encapsulate

them are non-linear and so require numerical techniques for their solution.

Typical Table Tennis Ball Speeds

DIAMETER (mm)	MASS RANGES (g)	SPEEDS (m/s)	RE	MAX SPINS (rps)	RE ?
38	2.51-2.54	17.8	45100	133.5	80750
40	2.65-2.80	17.0	45350	116.5	78100

Assumptions

The analysis presented here assumes a table tennis ball to be a uniform and smooth, spherical shell

possessing mass and rotational inertia. Motion is in a uniform, parallel gravitational field and stable

atmospheric conditions. The trajectories are 3-dimensional and observed from an inertial reference

frame in accordance with Newtonian mechanics.

News

Rowden — Mon, 28 Apr 2008 21:24:08 +0000

Looking ahead a little I shall be abroad coaching in Gothenburg, Sweden for around a month from the 23rd June, 2008. This is in Molndals club which is one of the most rapidly growing clubs in Sweden under the very capable direction of ‘Putte’ Andersson who is the’guru’ and leading light. I shall be involved in a number of summer camps with both Swedish and foreign players and shall be joined by a fair number of players from England who are anxious to improve and develop in a rather more professional environment than they normally experience. R