Table of contents | |
Time | |
Calendar | |
Temperature | |
Conversion from One Unit to Another |
Types of Clocks
Some units for measuring time are given below:-
Edurev Tips: 12 o’clock, noon time is written as 12 noon and 12 o’clock, midnight is written as 12 midnight. It is wrong to write 12 a.m. or 12 p.m.
A. Conversion of Minutes to Seconds
We know that,
Look at the following examples:
1 min = 1 × 60s = 60s; 3 min = 3 × 60s = 180s ; 10 min = 10 × 60s = 600s;
2 min 10s = 2 min + 10s = 2 × 60s + 10s = 120s + 10s = 130s
B. Conversion of Seconds to Minutes
We know that,
Look at the following examples:
180s = (180 ÷ 60) min = 3 min; 1200 s = (1200 ÷ 60) min = 20 min;
107s = 60s + 47s = 1 min 47s
Or 107s = (107 ÷ 60) min = 1 min 47s
C. Conversion of Hours to Minutes
We know that,
Look at the following examples:
3 h = 3 × 60 min = 180 min
1 h 45 min = 1 h + 45 min
= 1 × 60 min + 45 min
= 60 min + 45 min = 105 min
D. Conversion of Minutes to Hour
We know that,
Look at the following examples:
360 min = (360 ÷ 60) h = 6 h
230 min = (230 ÷ 60) h = 3 h 50 min
230 min = 180 min + 50 min
= (180 ÷ 60) h + 50 min = 3 h + 50 min = 3 h 50 min
E. Conversion of Seconds to Hours, Minutes and Seconds
Look at the following examples:
2105s = (2105 ÷ 60) min
= 35 min + 5s = 35 minutes 5 seconds
5430s = (5430 ÷ 60) min
= 90 min + 30s
= 60 min + 30 min + 30s
= 1 h 30 min 30 seconds
Edurev Tips:
- 60 seconds = 1 minute
- 1 second = 1 / 60 minute
- 60 minutes = 1 hour
- 1 minute = 1 / 60 hour
Example 1: Add 12 hours 27 minutes and 3 hours 58 minutes
We write the time in hours and minutes in separate columns. Add as you do for ordinary numbers.
Thus, 12 hours 27 minutes + 3 hours 58 minutes = 16 hours 25 minutes.
Think:
27 min+ 58 min = 85 min
= 60 min + 25 min
= 1 h + 25 min
Example 2: Add 1 hour 20 minutes 36 seconds and 2 hours 45 minutes 55 seconds.
Thus, 1 hour 20 minutes 36 seconds + 2 hours 45 minute 55 seconds
= 4 hours 6 minutes 31 seconds.Think:
36 s + 55 s = 91s
= 60 s + 31 s
= 1 min 31 s
20 min + 45 min + 1 min = 66 min
= 60 min + 6 min
= 1 h + 6 min
1 h + 2 h + 1 h = 4 h
Example 3: Subtract 12 minutes 25 seconds from 35 minutes 12 seconds.
Think:
You cannot subtract 25 s from 12 s, so borrow 1 min from 35 min.
1 min = 60 s; 60 s + 12 s = 72 s;
72 s – 25 s = 47 s.
Example 4: Doon Express took 26 hours 37 minutes 10 seconds in travelling from Dehradun to Lucknow. Due to a techincal fault the train had a total stoppage of 8 hours 49 minutes 55 seconds at different stations. For how much time was the train moving?
To find out the time the train was moving, we need to subtract the stoppage time from the total travelling time.
Thus, the train was moving for
17 hours 47 minutes 15 seconds.Think:
Borrow 1 min.
60 s + 10 s = 70 s
70 s – 55 s = 15 s
Borrow 1 h.
60 min + 36 min = 96 min
96 min – 49 min = 47 min
25 h – 8 h = 17 h
Example 5: Subtract: 2 hours 40 minutes 50 seconds from 4 hours 25 minutes 31 seconds.
Thus, 4 hours 25 minutes 31 seconds – 2 hours 40 minutes 50 seconds
= 1 hour 44 minutes 41 seconds.Think:
Borrow 1 min = 60 s from 25 min
You now have 91 s.
91 s – 50 s = 41 s 24 minutes remain in minutes.
Borrow 1 h = 60 minutes from 4 h.
You now have 84 minutes.
84 minutes – 40 minutes = 44 minutes
The 24-hour time notation is represented by a ‘24-hour clock’.
You already know that,Thus, 2:35 a.m. = 0235 hours; 10:30 a.m. = 1030 hours
5:25 p.m. = 1725 hours; 9:15 p.m. = 2115 hours.
Also, we have,
Sol: (a) The elapsed time is 2143 hours – 1652 hours.
Thus, the elapsed time is 4 hours 51 minutes.
(b) To find the elapsed time between 2:35 a.m and 5:30 p.m., first convert the time to 24-hour time.
Sol: Elapsed time =
2 : 35 a.m. = 0235 hours
5 : 30 p.m. = 1730 hours
Thus, the elapsed time is 14 hours 55 minutes.
Example 7: Using a 24-hour clock, find the time.
(a) 3 hours 10 minutes after 2030 hours
(b) 8 hours 15 minutes before 2:35 p.m.
Sol: (a) Add 3 hours 10 minutes to 2030 hours to find the required time.
20 hours 30 minutes + 3 hours 10 minutes
= 23 hours 40 minutes (11:40 p.m.).
(b) 2:35 p.m. = 1435 hours = 14 hours 35 minutes
∴ Required time = 14 hours 35 minutes – 8 hours 15 minutes
= 6 hours 20 minutes
Thus, the required time = 6 hours 20 minutes = 0620 hours (6:20 a.m.).
By studying the calendar, we know that
1 year = 12 months
5 years = (5 × 12) months = 60 months
3 years 7 months = 3 years + 7 months
= (3 × 12) months + 7 months
= 36 months + 7 months = 43 months
48 months = (48 ÷ 12) years = 4 years
25 months = 24 months + 1 month = 2 years 1 month
Example 8: A child is asked to complete two assignments in 4 weeks. He completed the first assignment in 2 weeks 3 days. How much time is left for him to complete the second assignment?
Sol: Remaining Time
Thus, the child has 1 week 4 days left to complete the second assignment.
Think:
0 < 3
Thus, borrow 1 week = 7 days.
7 days – 3 days = 4 days
Example 9: Ananya was 10 years 6 months old when her sister Tanya was born. Her sister is now 27 years 8 months old. How old is Ananya now?
Ananya’s present age = 27 years 8 months + 10 years 6 months
Thus, Ananya is presently 38 years 2 months old.Think:
8 months + 6 months
= 14 months
= 12 months + 2 months
= 1 year + 2 months
Temperature is the measure to describe how hot or cold something is.
We can find out how hot a soup is or how cool a drink is by measuring its temperature.
Sol: Step 1: Subtract 32. 122 – 32 = 90
Step 2: Multiply the difference by 5 / 9
∴ 122°F = 50°C
Conversion from Celsius to Fahrenheit.
Example 11: Convert 80°C to °F.
Sol: Step 1: Multiply by 9 / 5
Step 2: Add 32. 144 + 32 = 176
∴ 80°C = 176°F.
58 videos|112 docs|40 tests
|
1. How can I convert minutes to hours? |
2. How do I convert Celsius to Fahrenheit? |
3. How can I convert hours to seconds? |
4. What is the formula to convert Fahrenheit to Celsius? |
5. How do I convert days to hours? |
|
Explore Courses for Class 5 exam
|