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Reply	Anonymous says: The touch pads are simply lowered into the water before the race and attached to the wall. They are pressure pads that are calibrated precisely to register a pressure that is higher than the pressure of waves in the water. A swimmer can't just tap the pad. They have to forcibly push on it. At the Olympics, there are cameras placed exactly under the finish line looking up at the touch pads. It has an extremely high frame per second rate. The officials studied the tape and determined that Phelps did indeed win because he clearly touched first and exerted more pressure on the pads.Search youtube for this video."Phelps And Covic 100 Fly Finish In Frames"  (no votes) Tags: weather, technology.
	posted on 2008-10-09 15:25:00 | Report abuse

Reply	SciFi says: The pads are the most basic of pressure sensors, and while touching anywhere on the pad works it is best to touch in the centre. They are designed with an adjustable space between the two sides of the sensor, so you can adjust it to work only when a swimmer impacts it - there is quite a difference in the magnitude of the force. The ones used by local swimming clubs have been known to not register a touch when a swimmer hasn't hit it hard enough, but these are older (but not necessarily not as well maintained!) than Olympic grade ones and the swimmer is usually one of the younger, less experienced ones.I've not noticed if they do it at the Olympics but certianly with the events where the finish is not watched by cameras from above they also use one or two backup buttons pressed by the Official on that lane. The difference between the backup and automatic times can give a hint of malfunctions.They are aligned in the easiest of ways, everything made to the same size and any holes in the pool side they are attached to are made in a line.  (no votes) Tags: weather, technology.
	posted on 2008-10-09 17:32:00 | Report abuse

Reply	Peter Grant says: I remember an incident in Australia many years ago when a swimmer was clearly the first to break the 15min mark for 1500m by several seconds but failed to set off the electronic timing with the touch pad. Because of this he missed getting the world record. In track events the finish can't be determined by 'a sensor beam that can scan the finish line' because it would measure hands, hair, flies or whatever. Instead the finish is determined by a high frame rate slit camera (video these days) which effectively takes 1/1000 sec slices of the finish line. This allows the judges to see whose torso (the body apart from head, arms or legs) reached the line first. Race times are given in 1/100 sec but placings are decided to 1/1000 sec.  (no votes) Tags: weather, technology.
	posted on 2008-10-15 23:50:00 | Report abuse

Reply	Bela De Lune says: In fact the touchpads "learn" the difference between a human touch and the water's touch. They actually go to school for this - in a sense. After they are manufactured, They are hosed with heavy streams of water. The touch pads begin to choke. This is similar to "water boarding" Islamic terrorists. The pad then realizes it has not drowned and pays no further attention to water.After this the pad is subjected to human's punching it as hard as they can. The pad becomes bruised psychologically. It then becomes super-sensitive to any human touch and therefore always knows the difference. Also, touch pads are under water - so they don't feel waves you idiot.  (no votes) Tags: weather, technology.
	posted on 2008-11-07 08:33:00 | Report abuse

Reply	bks says: Bela De Luna referring to the poster of the question and other respondents as idiots, is well out of order, and I'm not sure that saying the touch-pads don't 'feel' waves because they are a surface phenomenon, is actually correct.Perhaps Bela can tell us how far under the surface of the water a bow-wave no longer produces a force ahead of a moving object, or, indeed, how the Indonesian tsunami ever happened, if waves are only a surface manifestation in an otherwise static mass of water.Are the pads actually 'under water', or are they placed so that contact can be made above the surface, in case the swimmer's hands are partway through the stroke when contact is made?  (no votes) Tags: technology, unanswered, domestic science, animals.
	posted on 2008-11-12 13:39:00 | Report abuse

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