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Research We have done a little physics research in the sport. Perhaps you would like to see our bowl flight trajectory on impact, in time lapse photography?
1. Flight trajectory after impact. 1. Flight trajectory after impact. Why is it so?
They certainly look and feel the same! Indeed, if you weighed them they are probably equivalent and yet they behave differently. To understand their differences, we must look inside. Before we venture in, lets review the two series of time lapse photos. Each series of photographs was taken under identical conditions, the only difference being in the ball chosen to investigate. In each case, the ball is released at the top of a steep incline. By examining the photographs, it is evident that on collision with the concrete base, the ball in the lower photograph rebounds significantly more than in the other case. After the collision this ball’s path through the air is such that it misses the opponent’s ball. However in the upper series, the lower rebound ensures that there is insufficient height to clear the opponent’s ball. Why do these balls bounce so differently? Imagine the following experiment where any elastic ball, similar to the first ball is bounced on a concrete base. After the first bounce, it reaches a certain height. By placing a piece of carpet over the base, we observe that it does not bounce as high. The carpet has absorbed some of the bounce. The cars we drive have similar devices, called shock absorbers. Without these, our cars would continuously oscillate (bounce) every time we went over a bump. This is where the answer lies. Inside one of these balls is a “shock absorber”, in the form of heavy beads of lead in an elastic filling. On collision, this filling material can move independently of the shell. In this way a large fraction of the energy from the impact is used up in rearranging this filling. Thus there is less energy available to allow the ball to bounce. Do you think they behave identically when they are given a spin?
Roger Rassool and Max Thompson 2. Well known Bowl Sports. How well do we compare with other Bowl Sports?
2.1 Bocce Bowls: Closest to the target Jack wins. Games are played
on a compacted sand surface 27.5m by 3 to 4m wide. The bowl is bowled for a
placement or after a run, thrown under arm to knock the opponents bowl, or the
jack, away. Game go end for end till the first to 13 points, wins. 2.2 Petanque Bowls: Closest to the target Jack wins. Games are played
on a bare surface, approximately in a 1.5m by 12m area. Bowls are thrown under
arm from a stationary position for a placement or to knock an opponents bowl
away. First to 13 points wins. 2.3 Raffa Bowls: Closest to the target Jack wins. Games are played
on a sand or artificial surface, 26.5m by 4.5m. Bowls are bowled under arm for
a placement or to knock an opponents bowl away, delivered along the court or
rebounding from the end and side boards. First to 15 points wins. 2.4 Lawn Bowls: Closest to the target Jack wins. Games are played on
a leveled grass or synthetic surface of 33m long by 5.8m wide. Bowls are bowled
under arm for a placement or to knock the opponents bowl or the jack away. The
bowl delivery curves, depending on the bowl bias, delivery style and surface
resistance. Games go end for end until first to 21 points wins.
2.5 Ten Pin Bowls: Most target Pins knocked down wins. Games are played on wood surfaced lanes, 18.3m long by 1.1m wide. Bowls are bowled underarm and the object is to knock down the 10 pins in a end. Players with most knock downs after 10 ends, wins. The descriptions are of a general nature for the respective games. Raymond Cher 3. Research papers on the sport. There isn't much published in english – but here is a start! 3.1 Method for testing artificial material for Bocce playing surface. A practical testing rig to test artificial surface material can be constructed using the results of this project. C. Cher, July 1993 3.2 Optimum size and weight of sport bocce bowls for players. What size and weight of bocce bowls are least affected by obstacles on the terrain. C. Cher, July 1992 3.3 Selection by thrower players as to the type of bowls and preferred playing surface. Investigation of filled and unfilled bocce bowls impacting on a variety of surfaces. (Physics – Extended practical investigation) C. Cher, July 1996 3.4 Shuttle Progressive Throw Seminar – The Technical Factors of Performance Christian Lacoste, National Technical Director FFSB, March 1998 3.5 Comparison of Filled and Unfilled Bocce Bowls flight trajectory after impact. (Time Lapse Photography) R. Cher, March 1995 The above papers are available to surfers with an inquiring mind and who want to know more about the mechanics of the sport. |
