Sunday, June 28, 2026

Motion in One Dimension Notes for NEET 2026 | Distance & Displacement MCQs with Solutions

 Motion in One Dimension – Rest, Motion & Frame of Reference (NEET Notes) 

Educational infographic explaining Motion in One Dimension with frame of reference, observer, distance, displacement, rest, motion, solved examples and NEET-level concepts.
Motion in One Dimension – Complete NEET Physics Notes on Frame of Reference, Distance, Displacement, Rest and Motion.


1. Can the Distance Between Two Places Be Fixed?

Example

Question: What is the distance between City A and City B?

Answer: This is an incomplete (incorrectly framed) question because the distance depends on the path or route taken.

For example:

  • Route 1 = 1050 km
  • Route 2 = 1510 km

Therefore, distance depends on the path followed.

Important: Always specify the route while asking about distance.

2. Frame of Reference

Definition

A frame of reference is a place or point from where we observe the position or motion of an object.

The person who makes the observation is called the observer.

Example

A student is standing on the roadside and watching a moving bus.

  • Road = Frame of reference
  • Student = Observer

3. Position

Definition

The position of an object is its location with respect to a frame of reference.

Example

A bicycle is parked 10 m from a tree.

Here,

  • Tree = Frame of reference
  • Bicycle = Object

4. Rest

Definition

An object is said to be at rest if its position does not change with time with respect to the chosen frame of reference.

Example

A school bag kept on a classroom desk is at rest with respect to the desk.

Position
  ^
  |
  |──────────────
  |
  +---------------------> Time

Position remains constant.

5. Motion

Definition

An object is said to be in motion if its position changes with time with respect to the chosen frame of reference.

Example

A car moving on a highway is in motion with respect to the road.

Position
  ^
  |        /
  |      /
  |    /
  +---------------------> Time

Position changes with time.

Relative Nature of Rest and Motion

Rest and motion are relative terms, not absolute.

They depend on the frame of reference.

Example

Suppose:

  • Student A is sitting inside a moving bus.
  • Student B is sitting beside Student A.
  • A traffic police officer is standing on the roadside.

Then:

  • Student A is at rest with respect to Student B.
  • Student B is at rest with respect to Student A.
  • Student A is in motion with respect to the traffic police officer.
  • Student B is also in motion with respect to the traffic police officer.

Thus, the same object can be at rest for one observer and in motion for another observer.

Important NEET Points

  • Frame of Reference: Place from where observation is made.
  • Observer: Person making the observation.
  • Position: Location of an object with respect to the frame of reference.
  • Rest: Position does not change with time.
  • Motion: Position changes with time.
  • Distance depends on the path taken.
  • Rest and motion are relative concepts.
  • There is no absolute rest or absolute motion in the universe.

NEET Quick Revision

  • Frame of Reference → Point from where observation is made.
  • Observer → Person who observes.
  • Position → Location relative to the reference point.
  • Rest → Position remains unchanged with time.
  • Motion → Position changes with time.
  • Distance → Depends on the path followed.
  • Rest and Motion → Relative, not absolute. 

Motion in One Dimension – Distance and Displacement (NEET Notes)

1. Observer Always Assumed to be at Rest

Definition

While studying motion, the observer is always assumed to be at rest with respect to the chosen frame of reference.

Example

A student is sitting inside a moving bus and asks,

"Sir, when will Delhi come?"

The teacher replies,

"Delhi is not coming. Our bus is moving towards Delhi."

Although it appears that Delhi is coming closer, actually the bus is moving, while Delhi is at rest with respect to the Earth.

Important Point

  • Motion is always described with respect to an observer.
  • The observer is usually considered to be at rest.

2. Distance

Definition

Distance is the actual length of the path travelled by an object.

OR

Distance is the total path covered by an object during its motion.

Formula

Distance = Actual Path Length

Characteristics of Distance

  • It depends on the path taken.
  • It is a Scalar Quantity (only magnitude, no direction).
  • It is always positive or zero.
  • It cannot be negative.
  • SI Unit = metre (m).
  • It is always greater than or equal to displacement.
  • Scalar quantities are added by simple algebraic addition.

Example 1

A person walks

  • 3 m forward
  • then 4 m forward

Distance = 3 + 4 = 7 m

Example 2

A person walks along three different paths between the same two points.

Path A = 10 m

Path B = 15 m

Path C = 18 m

Distance depends on which path is chosen.

3. Displacement

Definition

Displacement is the shortest straight-line distance between the initial position and the final position of an object.

OR

Displacement is the change in the position of an object.

Formula

Displacement = Final Position − Initial Position

Characteristics of Displacement

  • It depends only on the initial and final positions.
  • It does not depend on the path taken.
  • It is a Vector Quantity (has magnitude and direction).
  • It can be positive, negative, or zero.
  • SI Unit = metre (m).
  • To calculate displacement, only the initial position and final position are required.

Example 1

A person walks

  • 3 m east
  • then 4 m east

Distance = 7 m

Displacement = 7 m east

Since there is no change in direction,

Distance = Displacement

Example 2

A person walks

  • 3 m east
  • then 4 m west

Distance = 3 + 4 = 7 m

Displacement = 1 m west

Here,

Distance > Displacement

Example 3

A person starts from point A, walks around a circular park, and returns to point A.

Distance = Circumference of the park

Displacement = 0

Because the initial and final positions are the same.

4. Relation Between Distance and Displacement

Case 1: Straight-Line Motion (No Change in Direction)

Example

3 m → + 4 m →

Distance = 7 m

Displacement = 7 m

Distance = Displacement

Case 2: Motion with Change in Direction

Example

3 m → then 4 m ←

Distance = 7 m

Displacement = 1 m

Distance > Displacement

Important NEET Points

Distance Displacement
Actual path length Shortest straight-line distance
Scalar quantity Vector quantity
Depends on path Does not depend on path
Always positive or zero Can be positive, negative, or zero
Cannot be negative Can be negative
Distance ≥ Displacement Displacement ≤ Distance
Unit = metre (m) Unit = metre (m)

NEET Quick Revision

  • Observer → Usually assumed to be at rest.
  • Distance → Actual path travelled.
  • Displacement → Shortest straight-line distance between initial and final positions.
  • Distance depends on path.
  • Displacement depends only on initial and final positions.
  • Distance is a scalar quantity.
  • Displacement is a vector quantity.
  • Distance is always greater than or equal to displacement.
  • Distance = Displacement only when the object moves in a straight line without changing direction.
NEET Physics - Distance & Displacement (MCQ with Solutions)

Motion in One Dimension - Distance & Displacement (NEET Level)

Concept Questions with Solutions

Q1. Which of the following is always true for a moving object?
A) Distance = |Displacement|
B) Distance < |Displacement|
C) Distance ≥ |Displacement|
D) Distance ≤ |Displacement|
Answer: C) Distance ≥ |Displacement|
Explanation: Distance is actual path length, while displacement is shortest straight-line distance between initial and final points. So distance is always greater than or equal to displacement.
Q2. For motion in 1-D without change in direction, which is correct?
A) Distance = |Displacement|
B) Distance > |Displacement|
C) Distance < |Displacement|
D) None
Answer: A) Distance = |Displacement|
Explanation: When motion is in a straight line without reversing direction, actual path equals shortest path, so distance equals magnitude of displacement.
Q3. A person walks 4 m east and then 3 m east. Find distance and displacement.
Answer:
Distance = 4 + 3 = 7 m
Displacement = 7 m east
Explanation: Both motions are in same direction, so distance = displacement.
Q4. A person walks 6 m east and 4 m west. Find distance and displacement.
Answer:
Distance = 6 + 4 = 10 m
Displacement = 2 m east
Explanation: Distance adds total path. Displacement = final - initial = 6 - 4 = 2 m east.
Q5. Why is displacement a vector quantity?
Answer: Because displacement has both magnitude and direction.
Explanation: It depends on initial and final positions and includes direction (positive or negative in 1D).
Q6. Can distance be negative?
Answer: No.
Explanation: Distance is scalar and represents actual path length, so it is always positive or zero.
Q7. A body returns to its starting point after moving in a circle. Find distance and displacement.
Answer:
Distance = circumference of circle
Displacement = 0
Explanation: Final position = initial position, so displacement is zero but path is not zero.
Q8. What is frame of reference?
Answer: It is the point or system from which an observer measures position or motion.
Explanation: Motion is always relative to a chosen observer.
Q9. Why is motion relative?
Answer: Because it depends on the observer.
Explanation: An object may appear at rest for one observer and in motion for another.
Q10. A car moves 15 m straight without changing direction. Find distance and displacement.
Answer:
Distance = 15 m
Displacement = 15 m
Explanation: Straight-line motion without change in direction makes distance equal to displacement.

Key Formulas

  • Distance = Actual path length
  • Displacement = Final position - Initial position
  • |Displacement| ≤ Distance

Important Points

  • Distance is scalar
  • Displacement is vector
  • Distance depends on path
  • Displacement depends only on endpoints
Q11. A person walks 3 m north, then 4 m east. Find distance and displacement.
Answer:
Distance = 3 + 4 = 7 m
Displacement = √(3² + 4²) = √25 = 5 m (north-east direction)

Explanation:
Distance is total path length (scalar), so we simply add.
Displacement is shortest straight-line distance, so we use Pythagoras theorem because motion is at right angle.
Q12. A body moves 10 m forward and then 10 m backward. Find distance and displacement.
Answer:
Distance = 10 + 10 = 20 m
Displacement = 0 m

Explanation:
The object returns to its starting point, so final position = initial position.
Hence displacement is zero but distance is non-zero.
Q13. Which quantity can be zero even if an object moves? A) Distance B) Speed C) Displacement D) Time
Answer: C) Displacement

Explanation: If an object returns to its starting point, displacement becomes zero, but it still covers some distance.
Q14. A student says "Delhi is coming closer while we are in a train". Is this correct?
Answer: No, it is incorrect.

Explanation: Delhi is at rest with respect to Earth. The train is moving towards Delhi. Motion depends on frame of reference.
Q15. A particle moves in a straight line 8 m east and then 3 m west. Find displacement.
Answer:
Displacement = 8 - 3 = 5 m east

Explanation: Direction matters in displacement. East is positive, west is negative in 1D motion.
Q16. Why is distance always greater than or equal to displacement?
Answer:
Because distance is actual path and displacement is shortest path.

Explanation: Any curved or back-and-forth motion increases path length, so distance ≥ displacement always.
Q17. A car moves in a circular path and completes half a circle. Radius = 7 m. Find displacement.
Answer:
Displacement = diameter = 2 × 7 = 14 m

Explanation: In half circle, initial and final points are opposite ends of diameter.
Q18. Can displacement be greater than distance? A) Yes B) No
Answer: B) No

Explanation: Displacement is shortest distance, so it can never exceed actual path length.
Q19. A boy runs 5 m east, 5 m west, 5 m east again. Find distance and displacement.
Answer:
Distance = 5 + 5 + 5 = 15 m
Displacement = 5 m east

Explanation: Total path is added for distance, but final position is 5 m east of start.
Q20. Define observer in motion study.
Answer: The person who measures or observes the motion of an object is called an observer.

Explanation: All motion is described relative to the observer (frame of reference).
Q21. A particle moves 12 m north, then 5 m south. Find distance and displacement.
Answer:
Distance = 12 + 5 = 17 m
Displacement = 12 - 5 = 7 m north

Explanation:
Distance is total path length (scalar).
Displacement depends on direction, so we subtract opposite directions.
Q22. A body moves 6 m east, then 8 m north. Find displacement.
Answer:
Displacement = √(6² + 8²) = √(36 + 64) = √100 = 10 m (north-east)

Explanation:
Motion is at right angle, so we apply Pythagoras theorem.
Q23. If displacement is zero, what can we say about motion?
Answer: The object has returned to its initial position.

Explanation:
Even if the object moves, if final position = initial position, displacement becomes zero.
Q24. A car travels 20 m in a straight line. What is the relationship between distance and displacement?
Answer:
Distance = Displacement = 20 m

Explanation:
In straight-line motion without changing direction, path length equals shortest distance.
Q25. Which quantity gives only magnitude but no direction? A) Displacement B) Distance C) Velocity D) Acceleration
Answer: B) Distance

Explanation:
Distance is scalar, so it has only magnitude and no direction.
Q26. Can distance ever be negative?
Answer: No.

Explanation:
Distance is actual path length, so it is always positive or zero.
Q27. A person walks 10 m east and 10 m west. What is displacement?
Answer: 0 m

Explanation:
Final position is same as initial position, so displacement is zero.
Q28. What is the SI unit of displacement?
Answer: metre (m)

Explanation:
Displacement is a length quantity, so its SI unit is metre.
Q29. A student says “distance and displacement are always equal”. Is this correct?
Answer: No.

Explanation:
They are equal only in straight-line motion without change in direction.
Q30. A particle moves in a square path of side 4 m and returns to starting point. Find distance and displacement.
Answer:
Distance = 4 + 4 + 4 + 4 = 16 m
Displacement = 0 m

Explanation:
Distance is total perimeter, but displacement is zero because initial and final positions are same.
Q31. A car moves 18 m east and then 24 m north. Find displacement.
Answer:
Displacement = √(18² + 24²) = √(324 + 576) = √900 = 30 m (north-east)

Explanation:
Since motion is in two perpendicular directions, we use Pythagoras theorem to find shortest distance.
Q32. A body moves 15 m south and 15 m north. Find distance and displacement.
Answer:
Distance = 15 + 15 = 30 m
Displacement = 0 m

Explanation:
The object returns to its starting point, so displacement is zero.
Q33. Which statement is correct? A) Distance can be negative B) Displacement is always positive C) Distance is always ≥ |Displacement| D) Displacement is scalar
Answer: C) Distance is always ≥ |Displacement|

Explanation:
Distance is actual path length and cannot be less than shortest straight-line distance.
Q34. A student walks 7 m east, 7 m east, and 7 m west. Find displacement.
Answer:
Displacement = (7 + 7 - 7) = 7 m east

Explanation:
Take east as positive and west as negative, then add algebraically.
Q35. What is a frame of reference?
Answer: A system or point from which an observer measures position and motion.

Explanation:
Motion is always relative to a chosen reference point or observer.
Q36. A bus moves forward and a passenger feels stationary inside. Why?
Answer: Because both passenger and bus are in same frame of reference.

Explanation:
Relative motion inside the bus is zero, so passenger feels at rest.
Q37. A person completes one full circular path. What is displacement?
Answer: 0 m

Explanation:
Initial and final positions are same, so displacement is zero.
Q38. Which is vector quantity? A) Distance B) Speed C) Displacement D) Time
Answer: C) Displacement

Explanation:
Displacement has both magnitude and direction.
Q39. A body moves 9 m east and 12 m west. Find distance.
Answer: 21 m

Explanation:
Distance is total path length, so we add magnitudes.
Q40. Find displacement for Q39.
Answer: 3 m west

Explanation:
Net movement = 12 - 9 = 3 m towards west.
Q41. A particle moves 10 m east, 6 m north, and 10 m west. Find distance and displacement.
Answer:
Distance = 10 + 6 + 10 = 26 m
Displacement = 6 m north

Explanation:
Distance is total path length (scalar), so we add all parts.
East and west cancel each other (10 m east and 10 m west), leaving only 6 m north as net displacement.
Q42. A body moves in a straight line 25 m forward and then 25 m backward. Find displacement.
Answer: 0 m

Explanation:
Final position is same as initial position, so displacement becomes zero.
Q43. Which quantity depends on path taken? A) Displacement B) Position C) Distance D) Velocity
Answer: C) Distance

Explanation:
Distance depends on actual route followed, so different paths give different values.
Q44. A student says “displacement is always positive”. Is this correct?
Answer: No.

Explanation:
Displacement can be positive, negative, or zero depending on direction in 1-D motion.
Q45. A car moves 50 m straight without changing direction. What is true? A) Distance > Displacement B) Distance < Displacement C) Distance = Displacement D) Distance = 0
Answer: C) Distance = Displacement

Explanation:
In straight-line motion without reversing direction, path length equals shortest distance. 

Internal Links
• Units and Measurements Notes 
• Physical Quantities: Scalars and Vectors
 • Kinematics Complete Notes
 • Position, Distance and Displacement
 • Speed, Velocity and Acceleration
 • Graphs in Motion (Position-Time & Velocity-Time) 
• Relative Motion Explained
 • NCERT Class 11 Physics Chapter 3 Notes 
• NEET Physics Mock Tests
 • NEET Physics Previous Year Questions 
• Motion in a Straight Line Numericals 
• Laws of Motion Notes
 • Projectile Motion Notes
 • Circular Motion Basics
 • Physics Formula Sheet for NEET
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