[Maths Class Notes] on Stopwatches Pdf for Exam

Wondering what a stopwatch is? A stopwatch is a handheld timepiece designed to gauge the span of time which elapses between its activation and deactivation. In manual stopwatch time, the watch is started and stopped by a user pressing a button. However, in fully automatic timing, both starting and stopping are stimulated automatically, by sensors. Mechanical stopwatches are powered by a mainspring that should be wound up by turning the knurled knob located at the top of the stopwatch.

    

                             

How to Use a Stopwatch?

A big digital version of a stopwatch created for viewing at a distance, say like in a sports stadium, is known as a stop clock. The timing functions are conventionally controlled by the given two buttons on the case. Pressing the top button begins the timer running, and pressing the button a 2nd time stops it, keeping the elapsed time displayed. A press of the 2nd button then allows the stopwatch to reset to zero (0). This 2nd button is also used to monitor and record the split times or lap times. When you press the split time button while the watch is running it enables the elapsed time to that point to be read, but the watch apparatus continues running to record the total elapsed time. Pressing the split button a 2nd time will enable the watch to resume display of the total time.

Quick Guide To Knowing Mechanism of Stopwatches

• The “Play” button in a stopwatch begins from 00:00:00.00 in this format and the “…” button continues timing from whatever the time presently is.

• The Alarm goes off at 00:00:00.00. So the time should begin negative (with the “-” sign) in order to use the alarm.

• The time/alarm can be set with the help of sliders for hours, minutes and seconds.

• The “A”, “B”, etc button marks the time (without breaking up the timing)

Ideas For Timing in a Stopwatch

• You can time one individual, then press “+/-” and “…” , now the 2nd individual needs to finish before the alarm.

• Use the “A”, “B”, etc buttons in order to mark when runners finish (but let the overall timing keep going).

• You can begin a time-handicap race by establishing three alarms with different sounds, and then use the master “…” button in order to set them going at once.

Use of Stopwatches

Now you know what is a stopwatch, let’s get to know about its various uses and advantages of applications.

• Digital electronic stopwatches are far more accurate timepieces than mechanical because of their crystal oscillator timing element.

• Measures elapsed time much more accurately than is possible with the help of pressing the buttons

• Helps recording date and time-of-day functions with the presence of an inbuilt microchip.

• external sensors allow the stopwatch to be stimulated by external events,

Application of Stopwatches

• The device is used when time periods need to be measured precisely and with minimum complications. Laboratory experiments and sports events like sprints are classic examples of its application.

• The stopwatch function is also present in many electronic devices such as wristwatches, computers, cell phones, and portable music players.

Types of a Stopwatch 

Solved Examples

Example:

What fraction of a clockwise revolution will the hour hand of a stop clock turn through, when it goes from: 

1. 3 to 9

2. 4 to 7 

Solutions:

We know that in one complete revolution of clockwise direction, the hour hand will rotate by 3600

(a) When hour hand goes from 3 to 9 clockwise, it will either rotate by 2 right angles or 1800

∴ Fraction = 1800/3600

 = 1 / 2

(b) When the hour hand of the clock goes from 4 to 7 clockwise, it will rotate by 1 right angle or 900

Therefore, when we Fraction = 900 / 3600

We get,

= 1 / 4

Fun Facts

• You can set time for 1, 2 or 3 things at once in a stopwatch

• Each stopwatch contains an Alarm mode.

• You can also mark times for reading, sports events, work out etc.

• Stopwatches that count by 1/100 of a second are often inappropriate since counting milliseconds, instead of centiseconds.