Motion in Physics: Distance, Displacement, Speed and Velocity | JKSSB Finance Accounts Assistant

Motion is one of the most fundamental concepts in Physics and forms an important part of the General Science syllabus for the JKSSB Finance Accounts Assistant (FAA) examination. In our daily life, we observe various objects moving from one place to another, such as vehicles on roads, trains on tracks, and planets revolving around the Sun. Understanding how these objects move helps us study important concepts like distance, displacement, speed, and velocity.

Distance and displacement describe how far an object has moved, while speed and velocity explain how fast the object is moving. Although these terms appear similar, they have distinct meanings and are frequently tested in competitive examinations through conceptual and numerical questions.

In this article, we will learn the meaning, formulas, units, differences, and practical examples of distance, displacement, speed, and velocity in a simple and exam-oriented manner. The article also includes important formulas and  solved examples to help JKSSB FAA aspirants strengthen their preparation and score better in the General Science section.

Introduction to Motion

Motion refers to the change in the position of an object with respect to time. An object is said to be in motion if its position changes continuously or periodically relative to a reference point. For example, a moving car, a flying bird, a running athlete, and the Earth revolving around the Sun are all examples of motion.

The study of motion helps us understand how objects move and forms the foundation for many concepts in Physics. Concepts such as distance, displacement, speed, velocity, and acceleration are all based on the idea of motion.

Types of Motion (Brief Overview)

Motion can be classified into different types:

1. Linear Motion – Motion along a straight line, such as a train moving on a straight track.
2. Circular Motion – Motion along a circular path, such as the hands of a clock.
3. Rotational Motion – Motion in which an object rotates about its own axis, such as a spinning top.
4. Periodic Motion – Motion that repeats itself at regular intervals, such as the oscillation of a pendulum.

Distance: Meaning and Definition

Distance is one of the most basic concepts in Physics and is used to describe how much ground an object has covered during its motion. Whenever an object moves from one place to another, it travels along a certain path. The total length of this path is known as the distance travelled.

Distance does not take into account the direction of motion. It only tells us the total path covered by the object. Therefore, distance is concerned with “how much” an object has travelled and not “in which direction” it has moved.

For example, if a person walks 3 km east and then 4 km west, the total distance travelled is 7 km, regardless of the fact that the person changed direction during the journey.

Distance is the total length of the actual path travelled by an object between its initial and final positions, irrespective of direction.

Characteristics of Distance

1. Distance is a Scalar Quantity

A scalar quantity has only magnitude and no direction. Distance only tells us the length of the path travelled and does not indicate the direction of motion.

Example:
If a car travels 50 km, we know the magnitude of travel but not whether it moved north, south, east, or west.

2. Distance is Always Positive or Zero

Since distance represents the length of a path, its value can never be negative.

Example:
A person may move forward or backward, but the distance covered is always counted as a positive quantity.

3. Distance Depends on the Actual Path Travelled

Distance takes into account the complete route followed by an object.

Example:
Suppose a student travels from home to school using a winding road of 2 km. Even if the straight-line separation between home and school is only 1.5 km, the distance travelled is still 2 km because distance measures the actual path.

4. Distance Can Never Be Less Than Displacement

The distance travelled by an object is always greater than or equal to its displacement.

• Distance = Displacement when motion occurs in a straight line without changing direction.
• Distance > Displacement when the path is curved or involves a change in direction.

This is one of the most frequently asked conceptual questions in competitive examinations.

SI Unit of Distance

The SI unit of distance is metre (m).

Other commonly used units include:

Examples of Distance

Example 1: Walking to a Market and Returning

A person walks 5 km from home to a market and then returns 5 km back home.

Distance travelled:

Distance = 5 km + 5 km = 10 km

Although the person returns to the starting point, the total path covered is 10 km.

Example 2: Circular Track

A runner completes one full lap of a circular track measuring 400 m.

Distance travelled = 400 m

If the runner completes three laps:

Distance = 3 × 400 = 1200 m

Example 3: Moving Along Different Directions

A student walks:

• 2 km east
• 3 km north
• 1 km west

Total distance travelled:

Distance = 2 + 3 + 1 = 6 km

The direction of movement does not affect the calculation of distance.

Applications of Distance in Daily Life

Distance is used in many real-life situations:

• Measuring the distance between two cities.
• Determining the length of a road journey.
• Calculating fuel consumption of vehicles.
• Measuring race track lengths.
• Tracking the total path travelled by athletes and vehicles.

Important Points

• Distance measures the actual path travelled by an object.
• Distance is a scalar quantity.
• Distance has magnitude only and no direction.
• Distance is always positive or zero.
• Distance depends on the path followed.
• Distance can never be less than displacement.
• SI unit of distance is metre (m).
• Distance is equal to displacement only when motion occurs along a straight line in one direction.

If a person starts from a point, moves around, and finally returns to the same point, the distance travelled is not zero because the entire path covered is counted. However, the displacement becomes zero because the initial and final positions are the same.

Displacement: Meaning and Definition

Displacement is another important concept used to describe the motion of an object. While distance tells us the total path travelled, displacement tells us how far an object is from its starting point and in which direction. In other words, displacement measures the actual change in the position of an object.

Suppose a person starts from home, walks to a shop located 5 km east, and stops there. The distance travelled is 5 km and the displacement is also 5 km east because the person moved in a straight line without changing direction.

However, if the same person returns back home after reaching the shop, the total distance travelled becomes 10 km, but the displacement becomes zero because the initial position (home) and final position (home) are the same. This example clearly shows the difference between distance and displacement.

Displacement is the shortest straight-line distance between the initial position and the final position of an object, along with its direction.

The term “shortest distance” is very important. Regardless of the path taken, displacement always considers the direct straight-line path from the starting point to the ending point.

Characteristics of Displacement

1. Displacement is a Vector Quantity

Displacement has both magnitude and direction. Therefore, whenever displacement is expressed, the direction must also be mentioned.

For example:

• 10 km east
• 20 m north
• 5 km west

Simply writing “10 km” is not enough because displacement requires a direction.

2. Displacement Depends Only on Initial and Final Positions

Unlike distance, displacement does not depend on the actual path travelled by the object. It only depends on where the object started and where it ended.

For example, a student may take different roads to reach school. One route may be 2 km long while another may be 3 km long. Although the distances travelled are different, the displacement remains the same because the starting point (home) and ending point (school) are unchanged.

3. Displacement Can Be Positive, Negative, or Zero

The sign of displacement depends on the direction chosen as positive.

• If an object moves in the positive direction, displacement is positive.
• If it moves in the opposite direction, displacement is negative.
• If the object returns to its starting point, displacement becomes zero.

For example, if east is taken as positive:

• Moving 5 m east → +5 m displacement
• Moving 5 m west → –5 m displacement

4. Displacement is Never Greater Than Distance

The magnitude of displacement is always less than or equal to the distance travelled.

This is because displacement is the shortest path between two points, whereas distance is the actual path covered.

For example, if a person walks around a park and returns to the starting point:

• Distance travelled may be 500 m.
• Displacement is 0 m.

Therefore:

Displacement ≤ Distance

SI Unit of Displacement

The SI unit of displacement is metre (m).

Other commonly used units are:

• Kilometre (km)
• Centimetre (cm)
• Millimetre (mm)

Although both distance and displacement are measured in metres, they are different quantities because displacement includes direction.

Examples of Displacement

Example 1: Straight-Line Motion

A person walks 20 metres east.

• Distance = 20 m
• Displacement = 20 m east

Since the motion is along a straight line in one direction, distance and displacement are equal.

Example 2: Going and Returning

A person walks 8 km east and then 8 km west to reach the starting point.

• Distance = 16 km
• Displacement = 0 km

The displacement is zero because there is no net change in position.

Example 3: Circular Path

A runner completes one full lap of a circular track and returns to the starting point.

• Distance = Circumference of the track
• Displacement = 0

This is a frequently asked question in JKSSB and other competitive exams.

Applications of Displacement

The concept of displacement is used in many practical situations:

• GPS and navigation systems use displacement to determine the shortest route.
• Pilots and sailors use displacement to calculate their position relative to a starting point.
• Scientists use displacement while studying the motion of planets, satellites, and vehicles.
• Velocity calculations are based on displacement rather than distance.

Important Points

• Displacement is the shortest distance between the initial and final positions.
• It is a vector quantity.
• Direction is always required while expressing displacement.
• It depends only on the starting and ending positions.
• It can be positive, negative, or zero.
• Its magnitude can never exceed distance.
• SI unit of displacement is metre (m).
• If an object returns to its starting point, displacement becomes zero.

A runner may run 10 laps around a circular track and cover several kilometres of distance. However, if the runner finishes at the same point from where the race started, the displacement will still be zero because there is no overall change in position.

Difference Between Distance and Displacement

Distance and displacement are two closely related concepts in Physics, but they are not the same. Many students often confuse these terms because both are used to describe the motion of an object. However, distance measures the total path travelled, whereas displacement measures the shortest straight-line distance between the starting and ending points along with direction.

Understanding the difference between distance and displacement is very important because questions based on these concepts are frequently asked in JKSSB and other competitive examinations.

Distance vs Displacement

Understanding Through an Example

Consider a person who walks 5 km east from home to a market and then returns 5 km west back home.

Distance Travelled

Distance = 5 km + 5 km = 10 km

This is because distance measures the entire path travelled.

Displacement

Displacement = 0 km

The person returns to the starting point, so the initial and final positions are the same. Therefore, there is no net change in position.

Another Example

Suppose a student walks 8 metres straight towards the east.

• Distance = 8 m
• Displacement = 8 m east

In this case, distance and displacement are equal because the motion occurs in a straight line without changing direction.

Key Differences to Remember

1. Distance tells us how much path has been covered, whereas displacement tells us how far an object is from its starting point.
2. Distance ignores direction, while displacement always includes direction.
3. Distance can never be negative, but displacement may be positive, negative, or zero.
4. Distance depends on the actual route taken, while displacement depends only on the starting and ending positions.
5. If an object returns to its starting point, distance remains positive but displacement becomes zero.

Exam-Oriented Facts

• Distance is a scalar quantity; displacement is a vector quantity.
• Distance is always greater than or equal to displacement.
• Displacement can never be greater than distance.
• Distance and displacement become equal only when motion takes place along a straight line in one direction.
• For a complete circular path, displacement is zero while distance is equal to the circumference of the circle.

Speed: Meaning, Definition and Formula

Speed is a measure of how fast or slow an object is moving. In our daily life, we often use speed to describe the motion of vehicles, trains, airplanes, and even people. For example, when we say that a car is moving at 60 km/h, we are referring to its speed.

In Physics, speed tells us the distance travelled by an object in a given interval of time. The greater the speed, the more distance an object covers in a given time. Similarly, a lower speed means the object covers less distance in the same amount of time.

Speed is one of the most commonly used quantities in the study of motion and forms the basis for understanding many other concepts in Physics.

Speed is defined as the distance travelled by an object per unit time.

In simple words, speed indicates how quickly an object changes its position.

Formula of Speed

The mathematical formula for speed is:

Speed = Distance ÷ Time

or

v = d/t

Where:

• v = Speed
• d = Distance travelled
• t = Time taken

SI Unit of Speed

The SI unit of speed is:

metre per second (m/s)

Other commonly used units are:

• Kilometre per hour (km/h)
• Centimetre per second (cm/s)

Conversion Between Units

For competitive examinations, students should remember the following conversions:

• 1 m/s = 3.6 km/h
• 1 km/h = 5/18 m/s

These conversions are frequently used in numerical problems.

Types of Speed

1. Uniform Speed

An object is said to have uniform speed if it covers equal distances in equal intervals of time.

Example:
A train covers 60 km every hour throughout its journey. Its speed remains constant, so it is moving with uniform speed.

2. Non-Uniform Speed

An object has non-uniform speed if it covers unequal distances in equal intervals of time or equal distances in unequal intervals of time.

Example:
A car moving through city traffic speeds up and slows down frequently. Therefore, its speed is non-uniform.

3. Average Speed

When the speed of an object changes during its motion, average speed is used to describe its overall motion.

Average Speed = Total Distance Travelled ÷ Total Time Taken

For example, if a person travels 100 km in 2 hours, then:

Average Speed = 100 ÷ 2 = 50 km/h

Solved Example

A car travels a distance of 150 km in 3 hours.

Using the formula:

Speed = Distance ÷ Time

Speed = 150 ÷ 3

Speed = 50 km/h

Therefore, the speed of the car is 50 km/h.

Real-Life Applications of Speed

Speed is used in many practical situations:

• Determining the speed of vehicles on roads.
• Measuring the speed of trains and aircraft.
• Calculating travel time for a journey.
• Monitoring speed limits to ensure road safety.
• Studying the motion of athletes in sports.

Important Points

• Speed is the distance travelled per unit time.
• Speed is a scalar quantity because it has magnitude only and no direction.
• SI unit of speed is metre per second (m/s).
• Speed can never be negative.
• Uniform speed means equal distances are covered in equal intervals of time.
• Average speed is calculated using total distance and total time.
• Speed depends on distance, not displacement.

Two vehicles may have the same speed but move in different directions. Since speed does not include direction, both vehicles can still be said to have equal speed. Direction is considered only when we talk about velocity.

Velocity: Meaning, Definition and Formula

Velocity is one of the most important concepts in the study of motion. While speed tells us how fast an object is moving, velocity tells us both how fast and in which direction the object is moving. Therefore, velocity provides a more complete description of motion than speed.

For example, if a car is moving at 60 km/h, we know its speed. However, if we say the car is moving at 60 km/h towards the north, we are describing its velocity because the direction of motion is also specified.

Thus, velocity is closely related to displacement, just as speed is related to distance.

Definition of Velocity

Velocity is defined as the displacement of an object per unit time in a specified direction.

In simple words, velocity measures the rate at which displacement changes with time.

Formula of Velocity

The mathematical formula for velocity is:

Velocity = Displacement ÷ Time

or

v = s/t

Where:

• v = Velocity
• s = Displacement
• t = Time taken

SI Unit of Velocity

The SI unit of velocity is:

metre per second (m/s)

Other commonly used units are:

• Kilometre per hour (km/h)
• Centimetre per second (cm/s)

Although the SI units of speed and velocity are the same, they differ because velocity always includes direction.

Why Velocity is a Vector Quantity

Velocity possesses both:

1. Magnitude (how fast the object moves)
2. Direction (the direction of motion)

Therefore, velocity is classified as a vector quantity.

Examples:

• 20 m/s east
• 50 km/h north
• 10 m/s towards the south

Each of these examples includes both magnitude and direction.

Types of Velocity

1. Uniform Velocity

An object is said to have uniform velocity when it covers equal displacements in equal intervals of time without changing its direction.

Example:
A train moving in a straight line towards the east at a constant speed of 60 km/h has uniform velocity.

2. Variable Velocity

If either the speed or the direction of an object changes with time, its velocity changes.

Example:
A car moving through city traffic or a vehicle taking a curved path has variable velocity.

3. Average Velocity

Average velocity is defined as the total displacement divided by the total time taken.

Average Velocity = Total Displacement ÷ Total Time

Average velocity depends on displacement, not distance.

Solved Example

A person moves 120 metres east in 20 seconds.

Using the formula:

Velocity = Displacement ÷ Time

Velocity = 120 ÷ 20

Velocity = 6 m/s east

Therefore, the velocity of the person is 6 m/s east.

Difference Between Speed and Velocity Through an Example

Suppose a runner completes one lap of a circular track and returns to the starting point.

• Distance travelled = 400 m
• Displacement = 0 m

If the runner takes 100 seconds:

Speed = 400 ÷ 100 = 4 m/s

Velocity = 0 ÷ 100 = 0 m/s

This example shows that an object may have speed but zero velocity.

Real-Life Applications of Velocity

Velocity is used in:

• Navigation of ships and aircraft.
• GPS tracking systems.
• Weather forecasting to determine wind velocity.
• Studying the motion of planets and satellites.
• Calculating the movement of vehicles and projectiles.

Important Points

• Velocity is displacement per unit time.
• Velocity is a vector quantity.
• Velocity has both magnitude and direction.
• SI unit of velocity is metre per second (m/s).
• Velocity can be positive, negative, or zero depending on the direction of motion.
• Average velocity is based on displacement, not distance.
• An object can have constant speed but changing velocity if its direction changes.

When a car moves around a circular track at a constant speed, its velocity continuously changes because the direction of motion changes at every point on the circular path. This is why speed may remain constant while velocity changes.

Difference Between Speed and Velocity

Speed and velocity are closely related concepts in Physics and are often confused with each other. Both describe the rate of motion of an object and have the same SI unit, but they differ in an important aspect: speed considers only magnitude, whereas velocity considers both magnitude and direction.

Understanding the difference between speed and velocity is essential because questions based on these concepts are frequently asked in JKSSB and other competitive examinations.

Speed vs Velocity

Understanding Through Examples

Example 1: Straight-Line Motion

A car travels 60 km towards the east in one hour.

• Speed = 60 km/h
• Velocity = 60 km/h east

Here, speed only indicates the rate of motion, while velocity also specifies the direction.

Example 2: Circular Motion

A runner moves around a circular track at a constant speed.

Although the runner’s speed remains constant, the direction of motion changes continuously. Therefore:

• Speed remains constant.
• Velocity changes continuously.

This is a very important conceptual question in competitive examinations.

Example 3: Returning to the Starting Point

A person walks around a park and returns to the starting point.

• Distance travelled = 500 m
• Displacement = 0 m

If the journey takes 100 seconds:

• Speed = 500/100 = 5 m/s
• Velocity = 0/100 = 0 m/s

Thus, an object may have speed but zero velocity.

Key Differences to Remember

1. Speed is based on distance, whereas velocity is based on displacement.
2. Speed is a scalar quantity, while velocity is a vector quantity.
3. Speed does not require direction, but velocity cannot be expressed without direction.
4. Speed is always positive, whereas velocity may be positive, negative, or zero.
5. A change in direction affects velocity but may not affect speed.

Relationship Between Distance, Displacement, Speed and Velocity

Distance, displacement, speed, and velocity are the basic quantities used to describe the motion of an object. These concepts are interconnected and together provide a complete picture of how an object moves. To understand motion properly, it is important to know the relationship between these quantities rather than studying them separately.

Distance and displacement tell us how far an object has moved, while speed and velocity tell us how fast the object has moved. Distance is related to speed, whereas displacement is related to velocity.

How Distance is Related to Speed

Speed is the rate at which an object covers distance. In simple words, speed tells us how much distance an object travels in a given amount of time.

The formula for speed is:

Speed = Distance ÷ Time

From this formula, we can conclude that:

• If distance increases while time remains the same, speed increases.
• If time increases while distance remains the same, speed decreases.
• If an object covers more distance in less time, it is moving faster.

For example, consider two students travelling to school:

• Student A covers 10 km in 20 minutes.
• Student B covers 10 km in 40 minutes.

Since Student A covers the same distance in less time, Student A has a higher speed.

Thus, speed is directly connected with the distance travelled by an object.

How Displacement is Related to Velocity

Velocity is the rate of change of displacement with time. Unlike speed, velocity considers both magnitude and direction.

The formula for velocity is:

Velocity = Displacement ÷ Time

Since displacement includes direction, velocity also includes direction.

For example, if a person moves 100 metres east in 20 seconds:

Velocity = 100 ÷ 20 = 5 m/s east

If the same person moves 100 metres west in 20 seconds, the magnitude of velocity remains 5 m/s, but the direction changes.

This shows that velocity depends on displacement rather than distance.

Relationship Between Distance and Displacement

Distance and displacement both measure movement, but they do so in different ways.

Distance measures the actual path travelled by an object, whereas displacement measures the shortest straight-line distance between the starting point and the ending point.

Because the shortest distance between two points is always a straight line, the following relationship is always true:

Distance ≥ Displacement

Distance can never be less than displacement.

Case 1: Distance Equals Displacement

Distance and displacement become equal when an object moves along a straight line without changing direction.

For example:

A person walks 100 metres east in a straight line.

• Distance = 100 m
• Displacement = 100 m east

Since the path travelled and the shortest path are the same, both quantities are equal.

Case 2: Distance is Greater Than Displacement

Distance becomes greater than displacement whenever the object changes direction or follows a curved path.

For example:

A person walks:

• 5 km east
• Then 3 km west

Distance travelled:

Distance = 5 + 3 = 8 km

Final position:

The person is only 2 km east of the starting point.

Therefore:

• Displacement = 2 km east

Here:

Distance (8 km) > Displacement (2 km)

Relationship Between Speed and Velocity

Speed and velocity are closely related because both measure the rate of motion.

However:

• Speed is based on distance.
• Velocity is based on displacement.

Because distance is always greater than or equal to displacement, the numerical value of speed is always greater than or equal to the magnitude of velocity.

Therefore:

Speed ≥ Velocity (magnitude)

When Speed Equals Velocity

Speed and velocity become equal when motion occurs in a straight line without changing direction.

For example:

A car travels 60 km east in one hour.

• Speed = 60 km/h
• Velocity = 60 km/h east

Since the motion is straight and in one direction, both have the same numerical value.

When Speed is Greater Than Velocity

Speed becomes greater than velocity whenever the direction of motion changes.

For example:

A runner completes one full lap of a circular track.

Suppose:

• Distance travelled = 400 m
• Displacement = 0 m

If the runner takes 100 seconds:

• Speed = 400 ÷ 100 = 4 m/s
• Velocity = 0 ÷ 100 = 0 m/s

Thus, the runner has speed but zero velocity.

Key Relationships at a Glance

• Distance is used to calculate speed.
• Displacement is used to calculate velocity.
• Distance is always greater than or equal to displacement.
• Speed is always greater than or equal to the magnitude of velocity.
• Distance equals displacement only when motion is along a straight line in one direction.
• Speed equals velocity only when motion is along a straight line in one direction.
• If an object returns to its starting point, displacement becomes zero.
• When displacement is zero, average velocity also becomes zero.
• An object can have speed without having velocity.

Exam-Oriented Facts

• Distance and speed are scalar quantities.
• Displacement and velocity are vector quantities.
• Distance cannot be negative.
• Displacement can be positive, negative, or zero.
• Speed is always positive.
• Velocity may be positive, negative, or zero.
• In circular motion, speed may remain constant while velocity changes continuously due to change in direction.

Important Formulas for JKSSB FAA Exams

Formulas play a crucial role in solving numerical and objective questions in the General Science section. Although questions on motion are usually simple, aspirants often lose marks because they forget basic formulas or use the wrong quantity in calculations.

The concepts of distance, displacement, speed, and velocity are interconnected through a few fundamental formulas. By understanding these formulas and their applications, candidates can quickly solve examination questions.

1. Formula for Speed

Speed is defined as the distance travelled per unit time.

Speed = Distance ÷ Time

or

v = d/t

Where:

• v = Speed
• d = Distance travelled
• t = Time taken

Example:

A bus travels 150 km in 3 hours.

Speed = 150 ÷ 3

Speed = 50 km/h

2. Formula for Distance

Distance can be calculated when speed and time are known.

Distance = Speed × Time

or

d = v × t

Where:

• d = Distance
• v = Speed
• t = Time

Example:

A train moves at 60 km/h for 4 hours.

Distance = 60 × 4

Distance = 240 km

3. Formula for Time

Time can be calculated when distance and speed are known.

Time = Distance ÷ Speed

or

t = d/v

Where:

• t = Time
• d = Distance
• v = Speed

Example:

A car travels 180 km at a speed of 60 km/h.

Time = 180 ÷ 60

Time = 3 hours

4. Formula for Velocity

Velocity is defined as displacement per unit time.

Velocity = Displacement ÷ Time

or

v = s/t

Where:

• v = Velocity
• s = Displacement
• t = Time

Example:

A person moves 100 m east in 20 seconds.

Velocity = 100 ÷ 20

Velocity = 5 m/s east

5. Formula for Displacement

For simple motion in a straight line:

Displacement = Velocity × Time

or

s = v × t

Where:

• s = Displacement
• v = Velocity
• t = Time

Example:

A cyclist moves east with a velocity of 10 m/s for 5 seconds.

Displacement = 10 × 5

Displacement = 50 m east

Unit Conversion Formulas

Questions often require conversion between metre per second and kilometre per hour.

Convert m/s to km/h

1 m/s = 3.6 km/h

To convert m/s into km/h, multiply by 3.6.

Example:

20 m/s = 20 × 3.6 = 72 km/h

Convert km/h to m/s

1 km/h = 5/18 m/s

To convert km/h into m/s, multiply by 5/18.

Example:

72 km/h = 72 × 5/18 = 20 m/s

Formula Summary Table

Solved Examples on Distance, Displacement, Speed and Velocity

Understanding formulas alone is not enough for competitive examinations. Aspirants must also learn how to apply these formulas to solve numerical problems. The following solved examples will help you understand the concepts of distance, displacement, speed, and velocity in a simple and exam-oriented manner.

Example 1: Calculating Speed

Question:
A car travels a distance of 240 km in 4 hours. Find its speed.

Solution:

Given:

• Distance = 240 km
• Time = 4 hours

Using the formula:

Speed = Distance ÷ Time

Speed = 240 ÷ 4

Speed = 60 km/h

Answer: The speed of the car is 60 km/h.

Example 2: Calculating Distance

Question:
A train moves with a speed of 80 km/h for 5 hours. Calculate the distance travelled.

Solution:

Given:

• Speed = 80 km/h
• Time = 5 hours

Using the formula:

Distance = Speed × Time

Distance = 80 × 5

Distance = 400 km

Answer: The train travels 400 km.

Example 3: Calculating Time

Question:
A cyclist covers a distance of 90 km at a speed of 30 km/h. How much time does the journey take?

Solution:

Given:

• Distance = 90 km
• Speed = 30 km/h

Using the formula:

Time = Distance ÷ Speed

Time = 90 ÷ 30

Time = 3 hours

Answer: The cyclist takes 3 hours.

Example 4: Calculating Velocity

Question:
A person moves 150 metres east in 30 seconds. Find the velocity.

Solution:

Given:

• Displacement = 150 m east
• Time = 30 s

Using the formula:

Velocity = Displacement ÷ Time

Velocity = 150 ÷ 30

Velocity = 5 m/s east

Answer: The velocity of the person is 5 m/s east.

Example 5: Distance and Displacement

Question:
A student walks 4 km east and then 3 km west. Find the distance and displacement.

Solution:

Distance

Distance = 4 + 3

Distance = 7 km

Displacement

The student finally remains 1 km east of the starting point.

Displacement = 1 km east

Answer:

• Distance = 7 km
• Displacement = 1 km east

Example 6: Returning to the Starting Point

Question:
A runner completes one full lap of a circular track of circumference 500 m and returns to the starting point. Find the distance and displacement.

Solution:

Distance travelled = 500 m

Since the runner returns to the starting point:

Displacement = 0 m

Answer:

• Distance = 500 m
• Displacement = 0 m

Important Exam Point:
Whenever an object returns to its starting position, displacement becomes zero.

Example 7: Average Speed

Question:
A bus travels 120 km in 2 hours and then another 180 km in 3 hours. Calculate its average speed.

Solution:

Total Distance = 120 + 180 = 300 km

Total Time = 2 + 3 = 5 hours

Average Speed = Total Distance ÷ Total Time

Average Speed = 300 ÷ 5

Average Speed = 60 km/h

Answer: Average speed = 60 km/h

Example 8: Speed and Velocity Comparison

Question:
A person walks around a park and returns to the starting point after travelling 600 m in 10 minutes. Find the average speed and average velocity.

Solution:

Distance = 600 m

Displacement = 0 m

Time = 10 minutes

Average Speed

Average Speed = Distance ÷ Time

Average Speed = 600 ÷ 10

Average Speed = 60 m/min

Average Velocity

Average Velocity = Displacement ÷ Time

Average Velocity = 0 ÷ 10

Average Velocity = 0 m/min

Answer:

• Average Speed = 60 m/min
• Average Velocity = 0 m/min

Conclusion

Motion is one of the fundamental concepts in Physics and forms an important part of the General Science syllabus for the JKSSB Finance Accounts Assistant (FAA) examination. Understanding the concepts of distance, displacement, speed, and velocity is essential for solving both theoretical and numerical questions related to motion.

In this chapter, we learned that distance is the total path travelled by an object, while displacement is the shortest distance between its initial and final positions. Similarly, speed measures the distance travelled per unit time, whereas velocity measures displacement per unit time and includes direction. These concepts are closely related and help us describe how an object moves and how quickly it changes its position.

For examination purposes, aspirants should remember that distance and speed are scalar quantities, whereas displacement and velocity are vector quantities. They should also be familiar with the important formulas, unit conversions, and numerical applications discussed in this chapter.

A clear understanding of these concepts not only helps in answering objective questions but also builds a strong foundation for advanced topics in Physics. Regular revision of formulas, conceptual differences, and practice questions will significantly improve performance in JKSSB FAA and other competitive examinations.

Frequently Asked Questions (FAQs)

1. What is the difference between distance and displacement?

Distance is the total path travelled by an object, whereas displacement is the shortest straight-line distance between the initial and final positions along with direction.

2. Why is displacement called a vector quantity?

Displacement is called a vector quantity because it has both magnitude and direction.

3. Can distance and displacement be equal?

Yes. Distance and displacement are equal when an object moves in a straight line without changing its direction.

4. Can displacement be zero while distance is not zero?

Yes. When an object returns to its starting point, displacement becomes zero, but the distance travelled remains positive.

5. What is the SI unit of speed?

The SI unit of speed is metre per second (m/s).

6. What is the SI unit of velocity?

The SI unit of velocity is metre per second (m/s).

7. Why is speed a scalar quantity?

Speed is a scalar quantity because it has only magnitude and does not have any direction.

8. Why is velocity a vector quantity?

Velocity is a vector quantity because it has both magnitude and direction.

9. What is the formula for speed?

Speed = Distance ÷ Time

10. What is the formula for velocity?

Velocity = Displacement ÷ Time

11. Which is always greater: distance or displacement?

Distance is always greater than or equal to displacement.

12. Which is always greater: speed or velocity?

The numerical value of speed is always greater than or equal to the magnitude of velocity.

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Rohit Thapa

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