Introduction
Measuring time in ancient time?
Time was once measured using the lengths of shadows formed at different times of the day.
Modern way of measuring time: The modern convention is to divide it into 24 hours, An hour into 60 minutes, and a minute into 60 seconds.
Vocabulary:
- Day
- Hour
- Minute
- Second
Let’s understand the units of time with some daily basis time.
Today, the usual measuring instruments for time are clocks and watches.
Hours
Ask the following questions:
- How much time do you take to read?
Answer:- About an hour or even more.
- How much time do you play?
Answer:- About an hour or even more.
Minutes
- How much time do you take to drink a glass of milk?
Answer:- Just a few minutes.
- How much time does it take to comb hair?
Answer:- Just a few minutes.
Seconds
Very short durations are expressed in seconds which is the smallest time unit.
- How much time does it take to kick a ball?
Answer:- Just a second.
Units of time and relation between them
Conversion between the units of time
To convert from one unit of time to another unit, we need to multiply or divide.
Example 1
1. Convert 67 minutes into seconds.
Solution: 67 min = 67 × 60
= 4020 sec
2. Convert 4 ½ hours into minutes
Solution: 4 ½ hr = 4 × 60 + ½ × 60
= 240 + 30
= 270 min
3. Convert 250 minutes into hours and minutes.
Solution: 1 hr = 60 min or 60 min = 1 hr
250 min = 250/60
= 4 hr 10 min
4. Convert 81 hours into days and hours.
Solution: 1 day = 24 hr or 1 hr = 1/24 day
= 81 hr
= 81/24 hr
= 3 days 9 hr
Example: – Shelly took 1 hr 27 minutes to cook the food and 240 seconds to get ready for the office. Find the total time she has taken in minutes?
Solution: Shelly took 1 hr 27 minutes + 240 seconds
= 1 × 60 + 27 + 240/60
= 60 + 27 + 4
= 91 min
Concept Map
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