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# Time**|Definition & Meaning**

**Definition**

**Time** **represents** the **ordered** flow of **events** in the universe. It represents **past** **events** that have occurred, e.g., the writing of this article, **present** **events** occurring right now, e.g., you are reading this article, and **future** **events** that will occur, e.g., you continue reading this article. The **standard** **unit** of **time** is **seconds**, and we measure it with devices called clocks.

**Concept of Time**

Figure 1 – Time as a metric for doing certain events in our daily life (a timetable or schedule).

The **concept** of **time** flowing in a single direction, from the past to the present and into the future, is frequently **expressed** **mathematically** as a **continuous** **real** **number**. This understanding of time is predicated on the notion that the **universe** is **deterministic** and that **time** **behaves** according to **natural** **laws**.

There are many **tasks** in **daily life** that are **streamlined** with **time**, like there is a **specific** **time** to do **breakfast**, **lunch**, **dinner**, **work** and **sleep**. These tasks are illustrated in the figure above.

## Methods to Measure Time

Figure 2 – Visualizing a clock for realizing time

**Mechanical Clocks**

These **keep** **time** by using a **physical** **mechanism**, like a **pendulum** or a **spring**.

**Quartz Clocks**

These use an **oscillator** to keep time, and a **quartz** **crystal’s vibrations** **determine** the **frequency** of the oscillations.

**Atomic Clocks **

These offer **highly** **accurate** and **reliable** **time** measurements by using the vibrations of atoms.

**Sundials **

These **tell** the **time** by utilizing the **position** of the **sun**.

**Hourglasses**

**Sand** **moves** from one chamber to another in hourglasses, which use this method to measure time.

**Water Clocks**

These clocks use the movement of **water** from **one** **chamber** to **another** to measure time.

**Digital Clocks**

These are common in modern times and use **electronics** to **display** the time.

**Telling Time Using Clocks**

Figure 3 – Visualizing an analog or mechanical clock to tell time (3:00 am/pm).

A **clock** is a **tool** for **telling** the **time** by keeping track of the passage of time. There are two main categories of clocks: **analog** **clocks**, which use **hands** that revolve around a dial to show the time, and **digital** **clocks**, which use **numbers.**

**Analog Clock**

**Hour-and-minute** **hands**-on analog clocks **revolve** around a **dial**. The **minute** **hand** shows the **minutes**, while the **hour** **hand** shows the **hours**. With an analog clock, all you have to do to **tell** the **time** is look at **where** the **hour** and **minute** **hands** **are** in relation to the numbers on the dial.

**Digital Clock**

In digital clocks, the **hour**, **minute**, and **second** are **displayed** on a **screen** along with the time in **numerical** **form**. You only need to read the numbers on the screen of a digital clock to determine the time.

**Representation of Time in Mathematics**

**In Calculus**

Time is frequently used in **calculus** to describe a v**ariable’s rate of change. **

For instance, in **kinematics**, the **derivative** of an **object’s** **position** **with** respect to **time** can be used to **describe** an **object’s** **velocity**. This enables us to comprehend how things move and evolve over time. The **rate** at **which** **temperature** **changes** in relation to **time** can also be used to **describe** heat transfer in **thermodynamics**.

**As a Series of Discrete Events**

As a series of discrete events, time can also be represented in mathematics. **Time** is **divided** into a **series** of instants in this illustration, each of which represents a **single** **moment** in time. **Discrete** **mathematics** is **built** on this **foundation**, with an emphasis on the **connections** **between** these **events** and the laws governing their behavior.

**Physics**

**Time** is frequently thought of as a **dimension** in **physics**, similar to the three dimensions of space. This concept is fundamental to the theories of **special** and **general** **relativity**, which combine time and space into a single spacetime object with four dimensions. According to these theories, **time** and **space** **have** a **connection** and influence one another.

For instance, **time** may **appear** to **slow** **down** in the vicinity of a **large object** **due** **to** the **curvature** of **spacetime**.

**Geometry**

Time is a factor in the study of motion and change in geometry. A curve in spacetime, which **represents** the **path** of an **object** as it moves through space and time, is an illustration of how the idea of a curve in space can be expanded.

**Engineering, Finance, and Computer Science**

Time has useful applications in a wide range of disciplines, including engineering, finance, and computer science, in addition to mathematics. For instance, **time** is **used** in engineering to **simulate** **how** a **system** will **behave** over **time**, **enabling** engineers to **create** **systems** that are **more** **effective** and **efficient**.

Time is an **important** consideration in finance when **determining** **interest** **rates** and the **cost** of **financial** **instruments**. Time is used in computer science to **schedule**, **coordinate**, and **synchronize** processes that are running on various computers.

## Time on Number Line

On a **number** **line**, **time** is frequently **shown** as a **continuous** **progression** of **values** that **represent** the **passing** of **time**. To show how much time has passed, a **number** **line** that **starts** at **zero** and **grows over time** is typically used.

For instance, using a **24-hour format,** where **0** **represents** **midnight**, **12** **represents** **noon**, and **24** **represents** **midnight** once more, is a typical way to represent time on a number line. The progression of values on the number line in this format corresponds to the progression of hours, with each hour being represented by a single value.

The number line can **also** **show** **minutes** and **seconds** by **breaking** **down** **each** **hour** into **smaller** **chunks**. One **minute** can be represented by **60 equal parts,** each part representing one minute, for instance. In this way, the number line can show a specific time, like **2:15 PM,** as a **single value** that represents the number of minutes since midnight.

## Telling Time From an Analog Clock

An **analog clock’s hour** and **minute** hands **must** be **placed** in **relation** to the **numbers on** the **dial** in order to be read. The steps to reading the time on an analog clock are as follows:

The **hour hand** is typically the **shorter** of the **two hands** on the clock and points in the direction of the hour marks on the dial.

**Step 1**

**Find the hour:** To find the hour, **check where** the **hour hand** is in relation to the hour markers on the dial. The hour hand points to the hour mark, which denotes the current hour.

The **minute hand** is **typically** the **longer** one of the two hands on the clock and points in the direction of the minute marks on the dial.

**Step 2**

**Check** the **minute hand’s position** in relation to the minute marks on the dial to ascertain the time in minutes. The minute hand is pointing to the minute mark, which denotes the current minute.

**Step 3**

**Observe the time:** By **adding** the **hour** and **minute information,** the **time** can be **determined.** The time is **3:15,** for instance, **if** the **minute** hand is **pointing** toward the **15-minute** mark and the **hour hand** is pointing toward the **3 o’clock** position.

**An Example of Time on a Number Line**

**Observe** the **number line** and **tell** the **time** instance marked on it. What’s the **total time** spanned by this number line **?**

Figure 4 – Example of Time

**Solution**

We can see from the number line the current time is **3:20** **pm.**

Since the **extreme left** of the number line **shows 3:00** pm, and the **extreme right shows 3:45** pm, the **total time** spanned by this number line is **45 minutes.**

*All mathematical drawings and images were created with GeoGebra.*