Hour

What Is the Definition of an Hour?

An hour is one of the 24 equal parts of a day. 

1 hour $= 60$ minutes

             $= 3600$ seconds

Using the abbreviation of an hour, minutes, and seconds, we can write the above expression as:

1 h (or hr) $= 60$ min $= 3600$ sec

Let’s understand the concept of an hour more clearly with the help of a clock.

The numbers and the movement of the hour hand and minute hand on clocks help us calculate hours and the time, as well.

For example: Calculate the number of hours that have passed from Clock A to Clock B.

In the image given above, by looking at the two clocks—A and B—we can tell that:

• The hour hand in clock A is at 3, and the minute hand is at 12. (The time is 3 o’clock)
• The hour hand in clock B is at 5, and the minute hand is at 12. (The time is 5 o’clock)

Now, to calculate the number of hours from clock A to B, we need to subtract the number of the hour hand in Clock A from the number of the hour hand in Clock B.

$5$ $–$ $3 = 2$

Thus, 2 hours have passed from Clock A to Clock B.

How Many Hours Are in a Day?

24 hours make up a whole day. 

Numerically, we can write this as:

1 day $= 24$ hours

          $= 1440$ minutes

          $= 86,400$ seconds

More about Hour: History

In ancient times, when artificial lighting didn’t exist, people counted hours from sunrise and considered the middle of the day as the sixth hour’s end. 

The hours also varied in their length. These fluctuations occurred because changes in seasons and differences in location led to changes in the quantity of daylight and night hours.

It was only when artificial lighting and clocks were invented (which helped measure time accurately) that the practice of dividing days into equal-sized chunks based on the number of hours taken off.

Fun Facts!

• 168 hours make up a week.
• 8760 hours make up a year.
• In the past, sometimes, some people started counting the hours from sunset.

Conclusion

An hour is a unit of time that is equal to 60 minutes. 

In ancient times, it varied in length due to changes in seasons. Since there were no clocks and artificial lighting available, people counted the hours from sunrise. 

However, with the invention of timekeeping instruments, the scenario has changed. The number of hours no longer varies in length and remains fixed. Also, people keep track of time with the help of smart clocks and watches. 

Knowing the concept of the hour thus helps in calculating time.

Solved Examples

1. Sam has to leave for a meeting at 7 o’clock. Right now, it is 4 o’clock. How many hours are left before he has to leave?

Solution: To find the number of hours left for Sam to leave, we need to subtract 4 from 7. 

$7$ $-$ $4 = 3$.

So, Sam has 3 hours left before he has to leave for the meeting.

2. Find the number of hours present in 330 minutes.

Solution: 1 hour $= 60$ minutes.

To find out the number of hours in 330 minutes, we need to divide 330 by 60.

$\frac{330}{60} = 5.5$

This means there are 5 and a half hours (or 5 hours and 30 minutes) in 330 minutes.

3. Ken has ordered sets of different cookies. They will get delivered in 2 hours. He is curious to know how many seconds there are in 2 hours. Help him out by finding the answer.

Solution: We know that 1 hour $= 3600$ seconds.

So, 2 hours $= 2 \times 3600 = 7200$ seconds.

Thus, there are 7200 seconds in 2 hours.

4. How many hours are there in 4 days?

Solution: We know that 1 day $= 24$ hours.

So, 4 days $= 4 \times 24 = 96$ hours.

This means that there are 96 hours in 4 days.

5. How many milliseconds are there in 1 hour? (Hint: 1 second $= 1000$ milliseconds)

Solution: 1 hour time $= 3600$ seconds.

To find the number of milliseconds in an hour, we need to multiply 1000 by 3600.

$1000 \times 3600 = 3600000$.

Thus, in 1 hour, there are 3,600,000 milliseconds.

Practice Problems

Frequently Asked Questions

Related Article Links:

• Minute 
• Minute Hand 
• Second 
• Hour Hand 
• Day