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 Subject: watches Category: Science Asked by: perlu-ga List Price: \$5.00 Posted: 27 Apr 2002 03:25 PDT Expires: 04 May 2002 03:25 PDT Question ID: 6306
 ```what does a tachometer (tachy-?) really do on a wristwatch ? How do they work-if they do ?!```
 Subject: Re: watches Answered By: skis4jc-ga on 27 Apr 2002 09:41 PDT
 ```Dear Perlu, Thank you for your inquiry about watch tachometers! According to experts, a Tachometer, or Tachymeter, quite simply is a function on a watch that allows the user to measure speed. A Tachometer is a feature found on some chronograph watches, which measures the speed at which the wearer has traveled over a measured distance. In matchmaking, a timer or chronograph with a graduated dial on which speed can be read off in kilometers per hour or some other unit. For example, the tachometer division on the dial of a chronograph serves to measure the speed, e.g. of a car on a measured course of 1 km or 1 mile. At the moment the car passed the starting point of the course, the chronograph is set and stopped at the final point of the course. The position of the stopped hand on the tachometer scale corresponds to the speed in km (miles) per hour. The speed over the whole test run must be the same. This information was found at: FotoWatch http://www.fotowatch.com/glossary.htm#T Watch information from A to Z http://www.clockworks.com/watchaz3.html A site that advertises - “Call our experts” – 1 800 222 0077 World of Watches http://www.worldofwatches.com/ Search terms used: Tachometer Watch tachymeter Wristwatch vocabulary Thank you and have a great day! Best Regards, Skis4jc```
 ```A stopwatch with tachometer is very useful. For example, to measure the speed of a formula 1 race car, the time to cover a distance of 1000 meters is measured, and the tachometer scale automatically indicates the speed in kilometers per hour. A chrono that made particular good appearance in the racing world is the Rolex Cosmograph Daytona. It has a tachometer and a telemeter scale, as well as minute and hour registration```
 `Thanks ! I am confused at a higher level! NO-Greeat comments ,thanks again ! /Per`
 ```Perlu - I *think* what you might be asking is how does the mechanics of a tachometer work? I assume it's based on how pedometers work - these just measure distance. They work because when you run, at every step your body jolts up and down. They have a sensitive switch that will click on one more jolt with every step. Then you tell it how much ground you cover with that one step/pace. It counts how many steps you take and multiplies that by how far you cover. (If 1 pace = 1 yard, then 10 paces = 10 yards.) Now it knows how far you've travelled (eg 10 yards) (that's the pedometer bit). To turn this into a tachometer it also measures how long it took you to go "the full 10 yards". It divides 10 by the time taken (eg 5 seconds), giving you 2 yards per second. Oh yeah - a pedometer relies on the human jolting a switch with every footstep. Tachometers/odometers in a car or bike wouldn't count footsteps, they would count how many times one of the wheels does a full turn. If every full revolution of a wheel means the car/bike has moved 5 feet, then it multiplies the number of revolutions by 5. Hopefully that will give you an understanding at a lower level! Richard - London, UK```