- Time is measured using a clock. The dial of a clock is divided into 12 equal divisions marked as 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11 and 12.
(i) long hand and
(ii) short hand
The long hand is called minute hand and the short hand is called hour hand. Between two immediate numbers on the clock, the minute hand reads 5 minutes and the hour hand reads 1 hour.
- Some clocks have a third hand called second hand. It moves much faster than the other two hands.
- The hour hand takes 12 hours to complete one round on the dial of the clock.
- The minute hand takes 1 hour to complete one round on the dial of the clock.
- 1 hour = 60 minutes; 1 minute = 60 seconds.
So, 1 hour = 60 \[\times \] 60 = 3600 seconds.
- In short, minutes is written as min, hours as h and seconds as s.
- 1 day = 24 hours; 1 week = 7 days; 1 month = 4 weeks; 1 year = 12 months 1 year = 52 weeks; 1 year = 365 days
- The time from 12 midnight to 12 noon is read as a.m. (Anti Meridian) and the time from 12 noon to 12 midnight as p.m. (Post Meridian).
- A leap year has 366 days. In a leap year February has 29 days.
- The years 2000, 2004, 2008, 2012, 2016, 2020 etc. are leap years. A leap year come once in every 4 years.
- 30 days have September, April, June and November. All the rest have 31 days except February which has 28 days.
- The time (in minutes) that pass after an hour is read as minutes past hour.
2: 30 is read as 30 minutes past 2 or half-past 2.
- The length of the time (in minutes or hours) between two given times is called time duration.
e.g., The duration between 11: 45 a.m. and 12:15 p.m. is 30 minutes.