Clocks


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Clock


Important Rules :

Rule 1: Minute hand covers 360° in 1 hour, i.e., in 60 mins. Hence MINUTE HAND COVERS 6° PER MINUTE.

Rule 2: Hour hand cover 360° in 12 hours. Hence HOURS HAND COVERS 30° PER HOUR or 1/2° PER MINUTE.

Rule 3: In 1 minute, Minute hand covers 6° and hour hand covers 1/2°
∴ Relative speed = 6-1/2 = 5.5° per minute.

Rule 4: In 1 hour, minute hand covers 60 minutes divisions whereas hour hand covers 5 minutes divisions,
∴ Relative Speed = 60 – 5 = 55 minutes per hours.

Rule 5: In a period of 12 hours,
- The hands of clock coincides or make 0° with each other - 11 times
- Time gap between two successive cycles = 12/11 hrs = work (8) - The hands of clock are in straight line or make 180° with each other = 11 times
- The hands of clock make 90 or make any with each other = 22 times
Note - In rule 5, when we consider 1 day (24 hours) then every value will be DOUBLE ( Ex- 22 times, 22 times, 44 times respectively ).


Important Points :

* In 60 minutes, the minute hand gains 55 minutes on the hour on the hour hand.
* In every hour, both the hands coincide once.
* The hands are in the same straight line when they are coincident or opposite to each other.
* When the two hands are at right angles, they are 15 minute spaces apart.
* When the hands are in opposite directions, they are 30 minute spaces apart.
* Angle traced by hour hand in 12 hrs = 360°
* Angle traced by minute hand in 60 min. = 360°.
* If a watch or a clock indicates 8.15, when the correct time is 8, it is said to be 15 minutes too fast .
* On the other hand, if it indicates 7.45, when the correct time is 8, it is said to be 15 minutes too slow .
* The hands of a clock will be in straight line but opposite in direction, 22 times in a day
* The hands of a clock coincide 22 times in a day
* The hands of a clock are straight 44 times in a day
* The hands of a clock are at right angles 44 times in a day