Stopwatch
From Free net encyclopedia
A stopwatch is a timepiece designed to measure the amount of time elapsed from a particular time when activated and when the piece is deactivated.
Image:Stopwatch2.jpg Image:Stopwatch3.jpg The stopwatch is typically designed to start at the press of the top button and stop by pressing the button a second time to display the elapsed time. A press of the second button then resets the stopwatch to zero. The second button is also used to record split times or lap times. When the split time button is pressed while the watch is running, the display freezes, but the watch mechanism continues running to record total elapsed time. Pressing the split button a second time allows the watch to resume display of total time.
Mechanical stopwatches are powered by a mainspring, which must be periodically wound up by turning the knurled knob at the top of the watch.
Digital electronic stopwatches are available which, due to their crystal oscillator timing element, are much more accurate than mechanical timepieces. Because they contain a microchip, they often include date and time-of-day functions as well. Some may have a connector for external sensors, allowing the stopwatch to be triggered by external events, thus measuring elapsed time far more accurately than is possible by pressing the buttons with one's finger.
The device is used when time periods must be measured precisely and with a minimum of complications. Laboratory experiments and sporting events like sprints are good examples.
A large digital version of a stopwatch designed for viewing at a distance, as in a sports stadium, is called a stopclock.
The stopwatch function is also present as an additional function of many digital wristwatches. If an analog wristwatch has a stopwatch function, it is called a chronograph.
See also
de:Chronograph fr:Chronomètre nl:Stopwatch ja:ストップウオッチ nn:Stoppeklokke pl:Stoper (czasomierz) sr:Штоперица