📘 Chapter 2: Kinematics – Short Questions
Prepared by Muhammad Tayyab, Subject Specialist Physics, Govt Christian High School Daska. Based on PECTAA 2026 syllabus (National Curriculum 2023).
📖 What's Inside: This section covers short questions from Chapter 2 Kinematics including mechanics, scalars and vectors, representation of vectors, resultant vector, head-to-tail rule, rest and motion, types of motion, distance and displacement, speed, velocity, acceleration, graphs, equations of motion, gravitational acceleration, and the universal speed limit. Each question is presented with a precise answer as per the official PECTAA 2026 Physics curriculum. Perfect for Punjab Boards (Lahore, Gujranwala, Multan, etc.) and all BISE boards across Pakistan.
📚 Related Resources – Chapter 2: Kinematics
📋 Exercise Short Qs
📝 Short Qs
📖 Comprehensive Qs
🔢 Numerical Problems
✅ MCQs
✏️ Constructed Response
Kinematics covers motion, scalars, vectors, and graphical analysis of motion.
📝 Short Questions & Answers (PECTAA 2026)
1 Define mechanics and state its main branches.
Answer: Mechanics is the branch of physics that deals with the motion of objects and the forces that change it. Its two main branches are:
1. Kinematics: The study of motion of objects without referring to forces.
2. Dynamics: Deals with forces and their effect on the motion of objects.
✅ Mechanics: Kinematics (motion without forces) and Dynamics (forces and motion).
2 What is difference between scalar and vector quantities. Give 5 examples each for scalar and vector quantities.
Answer:
| Scalar Quantity | Vector Quantity |
|---|---|
| A scalar is that physical quantity which can be described completely by its magnitude only. | A vector is that physical quantity which needs magnitude as well as direction to describe it completely. |
| Examples: distance, length, time, speed, energy, temperature. | Examples: displacement, velocity, acceleration, weight, force. |
✅ Scalar: magnitude only (e.g., speed, distance). Vector: magnitude + direction (e.g., velocity, displacement).
3 How is a vector represented symbolically?
Answer: In the textbook, a vector is represented by a boldface letter such as A, v, F etc. Since boldface cannot be written on paper, a vector is written with a small arrow over it, i.e., \(\vec{A}\), \(\vec{v}\), \(\vec{F}\), \(\vec{d}\). The magnitude of a vector is represented by an italic letter without an arrowhead.
✅ Vector: boldface or with arrow over it (e.g., \(\vec{v}\)). Magnitude: italic without arrow.
4 What is a resultant vector, and how is vector addition different from scalar addition?
Answer:
Resultant Vector: A resultant vector is a single vector obtained by adding two or more vectors. It has the same effect as the combined effect of all the vectors being added.
Vector Addition vs. Scalar Addition: Unlike scalar addition, where only magnitudes are added, vector addition requires determining both magnitude and direction. One method of adding vectors is the graphical method.
✅ Resultant vector: single vector representing sum of vectors. Vector addition considers magnitude and direction.
5 State head-to-tail rule for addition of vectors.
Answer: To add a number of vectors, redraw their representative lines such that the head of one line coincides with the tail of the other. The resultant vector is given by a single vector which is directed from the tail of the first vector to the head of the last vector.
Figure: Head-to-Tail Rule for Vector Addition
✅ Head of one touches tail of the next. Resultant from first tail to last head.
6 What is difference between rest and motion?
Answer:
| Rest | Motion |
|---|---|
| If a body does not change its position with respect to its surroundings, it is said to be at rest. | If a body continuously changes its position with respect to its surroundings, it is said to be in motion. |
| Example: A motorcyclist standing on the road is at rest. | Example: A moving motorcyclist is in motion. |
✅ Rest: no change in position. Motion: continuous change in position.
7 Why is the state of rest or motion relative?
Answer: The state of rest or motion of a body depends upon the observer and the surroundings. For example, a person standing in a moving train is at rest with respect to passengers but in motion with respect to an observer on the platform.
✅ Rest and motion depend on the observer (relative).
8 What are the different types of motion? Explain with examples.
Answer: The three types of motion are:
1. Translatory Motion: Every particle of the body moves uniformly in the same direction. Example: motion of a train or a car.
2. Rotatory Motion: Each point of a body moves around a fixed point (axis). Example: motion of an electric fan or a spinning top.
3. Vibratory Motion: A body repeats its to and fro motion about a fixed position. Example: a swing in a children's park.
✅ Translatory (train), Rotatory (fan), Vibratory (swing).
9 What are the types of translatory motion? Explain with examples.
Answer: Translatory motion can be of three types:
1. Linear Motion: Body moves along a straight line. Example: a freely falling body.
2. Random Motion: Body moves along an irregular path. Example: motion of a bee.
3. Circular Motion: Body moves along a circle. Example: a Ferris wheel or a ball tied to a string and whirled in a circle.
✅ Linear (straight line), Random (irregular), Circular (circle).
10 Differentiate between distance and displacement.
Answer:
| Distance | Displacement |
|---|---|
| The distance is the length of the actual path of the motion. | The shortest distance between the initial and final positions of a body is called its displacement. |
| Distance is a scalar quantity. | Displacement is a vector quantity. |
✅ Distance: actual path length (scalar). Displacement: shortest distance (vector).
11 Define position.
Answer: Position of any object is its distance and direction from a fixed point.
✅ Position: distance and direction from a fixed point.
12 What is speed? Write its formula and SI unit.
Answer: Speed is the distance covered in unit time. It tells us how fast a body is moving.
The formula for speed \((v)\) is: \(\text{Speed} = \frac{\text{Distance}}{\text{Time}} = \frac{S}{t}\)
Speed is a scalar quantity, and its SI unit is ms⁻¹ or kmh⁻¹.
✅ Speed = S/t. SI unit: ms⁻¹ (scalar).
13 Differentiate between instantaneous speed and average speed.
Answer:
Instantaneous Speed: The speed of a vehicle at any given instant is called instantaneous speed. It is the reading shown on a speedometer at that moment.
Average Speed: Since speed is not constant during a journey, we often use average speed, which is defined as: \(v_{av} = \frac{S}{t}\). This helps us determine how fast an object moves on average over a period of time.
✅ Instantaneous speed: at a given instant. Average speed: total distance / total time.
14 What is velocity? Write its formula and SI unit.
Answer: Velocity is the net displacement of a body in unit time. It is a vector quantity, meaning it has both magnitude and direction.
The formula for average velocity is: \(v_{av} = \frac{d}{t}\)
The SI unit of velocity is ms⁻¹ or kmh⁻¹.
✅ Velocity = displacement/time. SI unit: ms⁻¹ (vector).
15 What is uniform and non-uniform velocity?
Answer:
Uniform Velocity: The velocity is said to be uniform if the speed and direction of a moving body do not change.
Non-uniform Velocity: If the speed or direction or both of them change, it is known as variable velocity or non-uniform velocity.
✅ Uniform: constant speed and direction. Non-uniform: speed or direction changes.
16 What is acceleration? Write its SI unit.
Answer: Acceleration is defined as the time rate of change of velocity. It is a vector quantity, meaning its direction is the same as that of the change in velocity.
The average acceleration is given by: \(a_{av} = \frac{v_f - v_i}{t} = \frac{\Delta v}{t}\)
The SI unit of acceleration is meter per second square (ms⁻²).
✅ Acceleration = change in velocity / time. SI unit: ms⁻².
17 What are the types of acceleration?
Answer: Acceleration is of two types:
1. Positive Acceleration: If the velocity is increasing, the acceleration is positive. For example, when a car overtakes another vehicle, it accelerates to a greater velocity.
2. Negative Acceleration (Deceleration or Retardation): If the velocity is decreasing, the acceleration is negative. For example, when brakes are applied to slow down a bicycle or a car, the velocity decreases.
✅ Positive: velocity increasing. Negative (deceleration): velocity decreasing.
18 What is uniform and non-uniform acceleration?
Answer:
Uniform Acceleration: If the time rate of change of velocity is constant, the acceleration is said to be uniform acceleration.
Non-Uniform Acceleration: If anyone of the magnitude or direction or both changes, the acceleration is called variable or non-uniform acceleration.
✅ Uniform: constant rate of change of velocity. Non-uniform: magnitude or direction changes.
19 What is a graph?
Answer: A graph is a pictorial diagram in the form of a straight line or a curve that shows the relationship between two physical quantities.
✅ Graph: pictorial diagram showing relationship between two quantities.
24 How are the axes selected, and what is meant by the origin in a graph?
Answer: To draw a graph, two mutually perpendicular thick lines, \(XOX'\) and \(YOY'\), are selected as the x-axis and y-axis. The point where the two axes intersect each other is known as the origin \((O)\).
Figure: Axes and Origin in a Graph
✅ Axes: XOX' (x-axis) and YOY' (y-axis). Origin: intersection point (O).
25 What are distance-time graph and speed-time graph?
Answer:
Distance-time Graph: A distance-time graph shows the relation between distance (S) and time (t) taken by a moving body.
Speed-time Graph: A speed-time graph shows the relationship between speed (v) and time (t) taken by a moving body.
Figure: Distance-Time Graph (left) and Speed-Time Graph (right)
✅ Distance-time: S vs t. Speed-time: v vs t.
26 What does the gradient of a speed-time graph represent?
Answer: Gradient of the speed-time graph is equal to the average acceleration of the body.
✅ Gradient of speed-time graph = average acceleration.
27 What does the area under a speed-time graph represent?
Answer: The area under the speed-time graph up to the time axis is numerically equal to the distance covered by the object.
Figure: Area under speed-time graph = Distance covered
✅ Area under speed-time graph = distance covered.
28 Write the three equations of motion.
Answer: Three equations of motion are:
\(v_f = v_i + at\)
\(S = v_i t + \frac{1}{2} at^2\)
\(2aS = v_f^2 - v_i^2\)
✅ 1st: \(v_f = v_i + at\), 2nd: \(S = v_i t + \frac{1}{2} at^2\), 3rd: \(2aS = v_f^2 - v_i^2\)
29 What is gravitational acceleration? OR What is free fall acceleration?
Answer: When a body falls freely under the action of Earth's gravity, the acceleration acting on it is called gravitational acceleration and is denoted by \(g\). The direction of gravitational acceleration is always downwards. Its value is \(9.8 \text{ms}^{-2}\), but for convenience, we use \(10 \text{ms}^{-2}\).
✅ Gravitational acceleration \(g = 9.8 \text{ms}^{-2}\) (downwards).
30 What points should be kept in mind while using equations for freely falling bodies?
Answer:
(i) If a body is released from some height to fall freely, its initial velocity \(v_i\) is taken as zero.
(ii) The gravitational acceleration \(g\) is taken as positive in the downward direction. All other quantities in the downward direction are also taken as positive, while those in the opposite direction are taken as negative.
(iii) If a body is thrown vertically upward, the value of \(g\) is negative, and the final velocity is zero at the highest point.
✅ For free fall: \(v_i = 0\), \(g\) positive downward. For upward motion: \(g\) negative, \(v_f = 0\) at highest point.
31 What is the universal speed limit?
Answer: According to Einstein's theory of special relativity, the speed of light is a universal constant. Its value is approximately \(3 \times 10^{8} \text{ms}^{-1}\), and any object with mass cannot achieve speeds equal to or greater than the speed of light. This is known as the universal speed limit.
✅ Universal speed limit: speed of light \(3 \times 10^{8} \text{ms}^{-1}\).
📐 Key Concepts – Kinematics
Mechanics: Kinematics (motion without forces) and Dynamics (forces and motion).
Scalar vs Vector: Scalar: magnitude only. Vector: magnitude + direction.
Types of Motion: Translatory, Rotatory, Vibratory.
Speed: \(v = S/t\) (scalar). Velocity: \(v = d/t\) (vector).
Acceleration: \(a = (v_f - v_i)/t\) (vector). SI unit: ms⁻².
Equations of Motion: \(v_f = v_i + at\), \(S = v_i t + \frac{1}{2} at^2\), \(2aS = v_f^2 - v_i^2\)
Gravitational Acceleration: \(g = 9.8 \text{ms}^{-2}\) (downwards).
💡 Exam Tip:
For short questions, always write precise and to-the-point answers. Use key terms like "mechanics", "kinematics", "dynamics", "scalar", "vector", "translatory", "rotatory", "vibratory", "speed", "velocity", "acceleration", "equations of motion", and "gravitational acceleration" as they are commonly tested in exams. These questions follow the PECTAA 2026 pattern and are prepared by Subject Specialist Muhammad Tayyab.
Chapter 1Physical Quantities and Measurements
Chapter 2✨ Kinematics
Chapter 3Dynamics
Chapter 4Turning Effect of Forces
Chapter 5Work and Energy
Chapter 6Mechanical Properties of Matter
Chapter 7Thermal Properties of Matter
Chapter 8Magnetism
Chapter 9Nature of Science
📖 Complete syllabus coverage for Class 9 Physics (PECTAA 2026) – Chapters 1 to 9
Created by Hira Science Academy | Aligned with PECTAA 2026 Syllabus