What is time? How is time measured? (Definition, Units & Examples) - BYJUS

# Understanding Time

Time is a quantity that moves only in one direction. We use time to remember the events that happened in the past, execute events of the present, and plan or schedule for future events. Time is one of the most valuable resources available to us. Learn the basic concepts of time to take control of this non-renewable resource....Read MoreRead Less ## What do we understand about time?

George and his mom are baking a birthday cake. As we know the baking process requires a fixed interval of time, they require a device that will remember this fixed time interval. Otherwise, they will either get an undercooked or overcooked cake. The ongoing sequence of events is referred to as “time.” The past, present, and future are all intertwined. The ”second” is the fundamental unit of time. Minutes, hours, days, weeks, months, and years are also included as units of time. We use clocks to keep track of time. Let’s look at some important terms associated with time:

Hour:  A period of 60 minutes.

1 day is made up of 24 hours.

Minute:  A period of 60 seconds.

1 minute is equal to 60 seconds.

Second : One of the 60 parts that make up a minute.

## Is it am or pm ?

The way time is read differs twice a day. This is because a day is made up of 24 hours and a clock has only 12 hours marked on it in case it’s an analog clock. But, a digital clock has digits to tell us the time. We use am and pm to tell us what part of the day it is and AM is used to denote the time after midnight, and PM is used to denote the time after noon or midday.

In alphabetical order, A comes before P. The same can be said about remembering AM and PM. As morning comes first, and then evening arrives as the sun sets, AM is morning and PM is any time after noon.

Example: 3 pm – Midday has passed and it’s time for basketball practice.

## Time to the nearest minute?

There are five minutes in the space between each number on a clock. You can tell the time by specifying the minute by looking at the position of the minute hand. We always count the minutes after an hour, which is represented by the “12” on the clock. There are 60 minutes in the space between 12 and 1 on a clock. We can tell the time according to the hour by looking at the position of the hour hand. The numbers 12, 1, and so on, represent the hour hand.

Example:  What is the time shown by clock? Answer:  Thou hour hand is between 4 and 5. So the hour is 4. Now let us find the minutes. The minute hand takes one minute to move from one mark to the next. From 12 to 1, we will measure 5 minutes. So, count 5s from 12 to 7. This is given as:

5 + 5 + 5 + 5 + 5 + 5 + 5 = 35 Then count from 7 to the mark where the minute hand is pointing. Therefore, total minutes are, 35 + 2 = 37.

So, the time is 4 hours: 37 minutes.

## Why do we need to represent time in different ways?

We represent time in different ways because it makes it easy for us to make sense of time. For example, 20 minutes before 7. It is clear that 20 minutes are left for the time to read 7 o’clock. Also, we can write, “6 hours and 40 minutes.”

For our convenience, we write it in different ways.

Count minutes after the hour: This is used with a specific number of minutes to indicate how long something will last after the hour begins.

Count minutes before the hour: The term “before the hour” is used with a specific number of minutes to indicate how long something will take place before the hour begins.

Example: What time is it on the clock?

What are some other ways to express time? Step 1: Observe the hour hand. The hour hand is at 8. So, the time is 8 hours.

Step 2: Observe the minute hand. The minute hand is close to 2 and also takes 1 space after 2 on the clock. Each space represents 1 minute. So, the time is 8 hours: 11 minutes.

We can write this in two different ways:

1)   By counting minutes before the hour: “11 minutes after 8”

2)  By counting minutes after the hour: “49 minutes before 9”

## What do we understand by elapsed time?

Elapsed time is the difference between the beginning and the ending times of any event.

Example:  You reach school at 8 am and you leave at 1 pm.

So, the elapsed time is 5 hours, that is, from 8 am to 1 pm.

There are two ways to define the elapsed time:

1)  Using an analog method: We find the elapsed time marking the starting time and end time on analog watches.

Example: Find the elapsed time between 3:04 P.M. to 3:23 P.M.?

Step 1: Draw the beginning and the ending times on an analog watch.  Step2: Count the minutes by 5s and 1s until we reach the ending time. So, the elapsed time is 19 minutes.

2)  Using a number line: We plot the starting and the ending times on the line. Then, we count until we reach it.

Example: Find the elapsed time between 7:00 pm. to 8:23 P.M.pm?

step 1: Draw the beginning and the ending times on the number line.  Step 2: Count the minutes by 5s and 1s until we reach the ending time. So, the elapsed time is 1 hour 23 minutes.

## Solved Examples of Time in Math

Example: Determine the time shown in the clock below. Step 1: Observe the hour hand. The hour hand is at 12. So, the time is 12 hours.

Step 2: Observe the minute hand. The minute hand is at 3. Each space represents 1 minute. So, from 12 to 1, we will count 5 minutes. From 1 to 2, we will count 5 minutes and from 2 to 3, we will count 5 minutes as well.

So, the time is 12 hours: 15 minutes.

Example: Olivia started playing at 4:14 am. She stopped playing at 5:19 am. How long did she play at the park?

As we can see from 4:14 to 5:00, she played for 46 minutes at the park.   From 5:00 to 5:19, she played for 19 minutes. So, the total time she spends playing is 1 hour 5 minutes, or 65 minutes.

Example: Find the elapsed time.

Start: 11:24 pm. End: 11:26 pm.  The elapsed time is 2 minutes, or 120 seconds.

Frequently Asked Questions on Time

Consider what it would be like if the entire planet had a single time zone. In some places, noon would be the middle of the day, while in others, it would be morning, evening, or even in the middle of the night. We need different time zones mainly because different parts of the Earth have daylight at different times.

Finding the elapsed time is an important skill in everyday life. Understanding how to read a clock and how we measure time are both necessary for calculating the elapsed time.

For example, we calculate the time spent on activities like playing, reading, and so on every day.