Hrs. | Min. |
10 – 5 |
30 00 |
5 | 30 |
Hrs. | Min. |
9 + |
15 30 |
9 | 45 |
Hrs. | Min. |
1 2 -10 | 0 0 1 5 |
1 | 4 5 |
Hrs. | Min. |
1 + 13 |
45 40 |
15 | 25 |
1 minute = 60 seconds
The clock in the picture above shows 5 minutes and 50 seconds past 3. 20 minutes and 10 seconds past 7
15 minutes and 40 seconds past 10
Seconds are used on various occasions such as measuring temperature with a thermometer, measuring heartbeats or timing a race.
Ante meridiem and post meridiem
Shripati was sitting at home at night, tired. There were guests at home. They asked, “You must have worked very hard in the fields today. How long were you working?”
Shripati said, “I was in the field from six o’clock to eight o’clock.” Someone asked, “You’re this tired even though you were in the field for only two hours?”
Shripati said, “No, no, I was in the field from 6 in the morning till 8 at night! Now tell me how many hours I spent in the field.”
The guests had not understood what Shripati said at first. To avoid such mistakes, it has been internationally agreed that as the clock strikes 12 midnight, one day ends and the next day begins. From that moment on, the clock shows the time for the next day. When one hour passes after 12 midnight, it is 1’o’clock. After that, it is 2, 3, 4, …, 12 o’clock in serial order. After 12 noon, again it is 1, 2, 3, …, 12 o’clock in serial order. The time before 12 noon is stated as ante meridiem or am. The time after 12 noon is stated as post meridiem or pm.
This method of measuring time is called the 12 hour clock.
Shripati was in the field from 6 am to 8 pm or for 14 hours.
The 24 hour clock
The 24 hour clock is used to avoid this division of the day into ante meridiem and post meridiem. This method is used in timetables for trains, planes, buses and long distance boat journeys. In this method, instead of starting again from 1, 2, 3 after 12 noon, we continue with 13, 14, 15,…,24. In a 24 hour digital watch, time is shown only in the form of numbers. It does not have hands. In such a clock, 20 minutes past 6 in the morning is shown as ‘6:20’ and 20 minutes past 6 in the evening is shown as ‘18:20’.
23:59 means 59 minutes after 23 and one minute later, 24 hours will be complete. The digital clock will show this time as 00:00 at midnight and the day will change. At that time, a 12 hour clock shows 12 midnight.
Study the following table to see how different times of the day are shown in the 12 hour and 24 hour clocks.
The timetables of some trains going from Badnera to Nagpur are given below. Observe the use of the 24 hour clock in the timetable.
Measuring Time Problem Set 43 Additional Important Questions and Answers
Write the time shown in each clock in the box given below it.
(1)
Answer:
15 minutes past 6
(2)
Answer:
30 minutes past 9
Draw the hands of the clock to sho the time given in the box.
(1) 5 minutes to four
Answer:
(2) 35 minutes past to 2
Answer:
(3) Sujata left home 6:30 and returned at 11. How much time did she spend away from home?
Solution:
Hrs. | Min* |
11 – 6 |
00 30 |
4 | 30 |
Hrs. | Min. |
5 + 4 |
4.5 20 |
1 | 25 |