FACTS  AND  FORMULAE  FOR  CLOCKS  QUESTIONS

 

 

The face or dial of a watch is a circle whose circumference is divided into 6 equal parts, called minute spaces.

 

A clock has two hands, the smaller one is called the hour hand or short hand while the larger one is called the minute hand or long hand.

 

1. In 60 minutes, the minute hand gains 55 minutes on the hour on the hour hand.

2. In every hour, both the hands coincide once.

3. The hands are in the same straight line when they are coincident or opposite to each other.

4. When the two hands are at right angles, they are 15 minute spaces apart.

5. When the hands are in opposite directions, they are 30 minute spaces apart.

6. Angle traced by hour hand in 12 hrs = 360°

7. Angle traced by minute hand in 60 min. = 360°.

 

Too Fast And Too Slow : If a watch or clock indicated 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.

Q:

A clock is set right at 8 a.m. The clock gains 10 minutes in 24 hours will be the true time when the clock indicates 1 p.m. on the following day?

A) 48 min. past 12. B) 46 min. past 12.
C) 45 min. past 12. D) 47 min. past 12.
 
Answer & Explanation Answer: A) 48 min. past 12.

Explanation:

Time from 8 a.m. on a day to 1 p.m. on the following day = 29 hours.

24 hours 10 min. of this clock = 24 hours of the correct clock.

 hrs of this clock = 24 hours of the correct clock.

29 hours of this clock =  hrs of the correct clock

= 28 hrs 48 min of the correct clock.

Therefore, the correct time is 28 hrs 48 min. after 8 a.m.

This is 48 min. past 12.

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180 33450
Q:

At what time between 4 and 5 o'clock will the hands of a watch point in opposite directions?

A) 54 past 4 B) (53 + 7/11) past 4
C) (54 + 8/11) past 4 D) (54 + 6/11) past 4
 
Answer & Explanation Answer: D) (54 + 6/11) past 4

Explanation:

4 o'clock, the hands of the watch are 20 min. spaces apart.
To be in opposite directions, they must be 30 min. spaces apart.
Minute hand will have to gain 50 min. spaces.
55 min. spaces are gained in 60 min

50 min. spaces are gained in  min. or 

 Required time =  min. past 4.

 

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91 25367
Q:

An accurate clock shows 8 o'clock in the morning. Through how may degrees will the hour hand rotate when the clock shows 2 o'clock in the afternoon?

A) 360 B) 180
C) 90 D) 60
 
Answer & Explanation Answer: B) 180

Explanation:

Angle traced by the hour hand in 6 hours=(360/12)*6

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16 19628
Q:

A clock is set right at 5 a.m. The clock loses 16 minutes in 24 hours.What will be the true time when the clock indicates 10 p.m. on 4th day?

A) 11pm B) 12pm
C) 1pm D) 2pm
 
Answer & Explanation Answer: A) 11pm

Explanation:

Time from 5 am. on a day to 10 pm. on 4th day = 89 hours.

Now 23 hrs 44 min. of this clock = 24 hours of correct clock.

356/15 hrs of this clock = 24 hours of correct clock

89 hrs of this clock = (24 x 31556 x 89) hrs of correct clock.

= 90 hrs of correct clock.

So, the correct time is 11 p.m.

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54 18191
Q:

A watch which gains uniformly ,is 5 min,slow at 8 o'clock in the morning on sunday and it is 5 min 48 sec.fast at 8 p.m on following sunday. when was it correct?

A) 7pm on wednesday B) 20 min past 7pm on wednesday
C) 15min past 7pm on wednesday D) 8pm on wednesday
 
Answer & Explanation Answer: B) 20 min past 7pm on wednesday

Explanation:

This sunday morning at 8:00 AM, the watch is 5 min. Slow, and the next sunday at 8:00PM it becomes 5 min 48 sec fast.  The watch gains  min in a time of  (7×24)+12 = 180 hours. 

To show the correct time, it has to gain 5 min.

So the correct time will be shown on wednesday at 7:20 PM

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46 16987