11th Class Physics Chapter 3 Notes | Get Now

September 1, 2026 Zain Javed 7 Views

11th Class Physics Chapter 3 Notes are an essential resource for every FSc Part 1 student studying under the Punjab Board syllabus. Chapter 3 is titled Motion and Force, and it is one of the most formula-heavy and numerically important chapters in the entire course. From Newton’s laws to projectile motion, this chapter tests both your conceptual understanding and problem-solving skills.

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The chapter covers velocity, acceleration, momentum, impulse, collisions, and projectile motion — all topics that appear in both short questions and numerical problems in board exams. A solid grip on this chapter builds the base for all mechanics topics in both FSc Part 1 and Part 2.

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For more chapter-wise resources, visit [internal link] for complete 1st Year Physics notes on TaleemWorld.com.

What Is Covered in Chapter 3 – Motion and Force?

The chapter is split into two main parts: short questions (3.1 to 3.14) and solved numerical problems (3.1 to 3.15). Both sections carry significant weightage in board examinations.

Key Topics in 11th Class Physics Chapter 3 Notes

Uniform and Variable Velocity – Definitions and differences
Acceleration – Rate of change of velocity, SI unit = m/s²
Newton’s Second Law in Terms of Momentum – F = rate of change of momentum
Impulse – Product of force and time; impulse = change in momentum
Law of Conservation of Linear Momentum – Total momentum of isolated system remains constant
Elastic and Inelastic Collisions – KE conserved vs not conserved
Projectile Motion – Time of flight, range, maximum range at 45°
Equations of Motion – All three kinematic equations applied in problems

Important Short Questions From Chapter 3

The short questions section of 11th Class Physics Chapter 3 Notes includes 14 conceptual questions. These are highly repeated in Punjab Board exams. Here is a breakdown of the most important ones:

Q 3.1 – Difference Between Uniform and Variable Velocity

Uniform Velocity: A body covers equal displacement in equal intervals of time
Variable Velocity: A body covers unequal displacement in unequal intervals of time
Acceleration: Rate of change of velocity, derived from variable velocity: a = Δv / Δt
SI unit of velocity: m/s, SI unit of acceleration: m/s²

Q 3.2 – Sign of Acceleration Due to Gravity

When an object is thrown vertically upward, acceleration due to gravity is negative relative to velocity. When the object moves downward, both velocity and acceleration are in the same direction, so acceleration is positive.

Q 3.4 – Correct Statements About Velocity and Speed

(a) False — speed and velocity are different quantities
(b) True — circular motion: constant speed, changing velocity
(c) True — at maximum height, velocity = 0 but a = g ≠ 0
(d) True — a ball thrown upward reverses direction with constant gravitational acceleration

Q 3.7 – Constant Velocity as Special Case of Constant Acceleration

Yes, this statement is true. When a body moves with constant velocity, its acceleration is zero. Since zero is a constant quantity, motion with constant velocity is a special case of motion with constant acceleration.

Q 3.8 – Change in Momentum and Newton’s Second Law

From F = ma and the equations of motion:

F = (mvf − mvi) / t = Rate of change of momentum

Newton’s Second Law in terms of momentum: The rate of change of momentum is equal to the applied force.

Q 3.9 – Define Impulse and Its Relation to Linear Momentum

Impulse: When a very large force acts on a body for a very short time, the product of that force and time is called impulse.

Impulse = F × Δt
I = mvf − mvi = ΔP = Change in momentum

This shows that impulse equals the change in linear momentum.

Q 3.10 – Law of Conservation of Linear Momentum

The total linear momentum of an isolated system remains constant. This law holds strictly for isolated systems (no external force). However, if external forces are very small compared to interacting forces, the law can still be approximately applied.

Q 3.11 – Elastic vs Inelastic Collisions

Elastic Collision: Kinetic energy remains constant
Inelastic Collision: Kinetic energy does not remain constant
In case of a bouncing ball: returns to same height → elastic; does not return → inelastic
Momentum is conserved in all types of collisions; KE is conserved only in elastic collisions

Q 3.12 – Projectile Motion

Projectile Motion is two-dimensional motion under constant acceleration due to gravity. The object is called a projectile and its curved path is called a trajectory.

Time of Flight:

t = 2vᵢ sin θ / g

Range of Projectile:

R = vᵢ² sin 2θ / g

Maximum Range: Range is maximum when θ = 45° because sin 2(45°) = sin 90° = 1, giving:

Rmax = vᵢ² / g

Q 3.13 – Minimum and Maximum Speed of a Projectile

The speed of a projectile is maximum at the point of projection and when it hits the ground. The speed is minimum at the maximum height (only horizontal component remains).

Solved Problems in 11th Class Physics Chapter 3 Notes

There are 15 fully solved problems in Chapter 3. These cover all major formulas and are based on the types of numerical questions asked in board exams. Here are the most important ones:

Problem 3.1 – Stone Dropped from a Helicopter

A helicopter ascending at 19.6 m/s drops a stone from 156.8 m height. Using the 2nd equation of motion:

S = vᵢt + ½gt²

Result: Time taken = t = 8 sec.

Problem 3.2 – Velocity-Time Graph of a Motorcyclist

Using given velocity-time data:

Initial acceleration = aᵢ = 0.33 m/s²
Final acceleration = af = −0.67 m/s²
Total distance = 2.7 km

Problem 3.3 – Retardation of a Proton Through Paper

Using 3rd equation of motion (2as = vf² − vi²):

Retardation = a = −2.4 × 10¹⁷ m/s²
Time taken = t = 3.3 × 10⁻¹¹ sec.

Problem 3.4 – Two Masses Released by a Compressed Spring

Using law of conservation of momentum:

v₁/v₂ = −m₂/m₁

The ratio of velocities is equal to the inverse ratio of their masses.

Problem 3.6 – Conservation of Momentum in Explosion

A firecracker in a 40g can explodes at top of path. Using conservation of momentum:

Speed of can = v₁’ = 15 m/s (opposite direction to block)

Problem 3.7 – Electron Collides with Hydrogen Atom

Perfectly elastic collision, using formula:

v₂’ = 2m₁v₁ / (m₁ + m₂)

Result: Velocity of hydrogen atom = 2.18 × 10⁴ m/s

Problem 3.8 – Truck and Car Collision (Inelastic)

Using conservation of momentum:

v = (m₁v₁ + m₂v₂) / (m₁ + m₂) = 15 m/s

Problem 3.10 – Initial Speed for a 40 m Football Pass

θ = 30°, R = 40 m, g = 9.8 m/s²

Using R = vᵢ² sin 2θ / g:

Result: Initial velocity = vᵢ = 21.3 m/s

Problem 3.11 – Ball Thrown Horizontally

vix = 21 m/s, height = 10 m

Horizontal distance = 30 m
Velocity at ground = 25 m/s

Problem 3.12 – Bomb Dropped from Bomber

Height = 490 m, horizontal speed = 300 km/h = 83.3 m/s

Horizontal distance = 833 m
Time in air = 10 sec.

Problem 3.15 – SLBM Missile Fired 3000 km Away

θ = 45°, horizontal distance = 3 × 10⁶ m

Velocity of missile = vᵢ = 5.42 km/s
Time taken = 13 min.

How to Study 11th Class Physics Chapter 3 Effectively

Using 11th Class Physics Chapter 3 Notes strategically will help you score better in board exams. Here are some practical tips:

Start with short questions — Questions 3.7, 3.8, 3.9, 3.10, and 3.12 are the most frequently asked
Learn all three equations of motion — They appear in almost every numerical problem
Understand projectile motion deeply — Time of flight, range, and maximum range are must-know derivations
Practice the collision problems — Problems 3.7 and 3.8 are based on elastic and inelastic collisions
Memorize the impulse-momentum relation — I = ΔP is asked both in theory and numerics
Solve past board papers — Match questions with these notes to see which are repeated most

You can also check [internal link] for more Physics chapter notes on TaleemWorld.com following the same format.

Why These Notes Are Perfect for Punjab Board Students

These 11th Class Physics Chapter 3 Notes are written specifically for the Punjab Board (BISE) syllabus and follow the exact pattern of FSc Part 1 annual exams. Features include:

All 14 short questions answered completely
15 fully solved numerical problems with data, formula, working, and result
Projectile motion derivations with clear formulas
Conservation of momentum problems solved step by step
Velocity-time graph questions explained

FAQs – 11th Class Physics Chapter 3 Notes

Q1: What is Chapter 3 of 11th Class Physics about?
Chapter 3 of 11th Class Physics is titled Motion and Force. It covers uniform and variable velocity, acceleration, momentum, impulse, elastic and inelastic collisions, and projectile motion. These topics form the core of mechanics and are heavily tested in Punjab Board annual exams.

Q2: Where can I get 11th Class Physics Chapter 3 Notes for Punjab Board?
You can get complete 11th Class Physics Chapter 3 Notes on TaleemWorld.com. The notes include all 14 short questions with full answers and 15 solved numerical problems, all aligned with the Punjab Board FSc Part 1 syllabus.

Q3: How many problems are solved in Chapter 3 Physics 11th Class?
There are 15 solved problems in Chapter 3 of 11th Class Physics. These include problems on equations of motion, conservation of momentum, elastic collisions, projectile motion, and time of flight calculations.

Q4: What is the formula for the range of a projectile in Chapter 3?
The range formula for a projectile is R = vᵢ² sin 2θ / g. The range is maximum when the projectile is thrown at 45° to the horizontal. This formula and derivation are explained in detail in Chapter 3 short question 3.12.

Q5: What is impulse and how is it related to momentum in Chapter 3?
Impulse is the product of a large force acting for a very short time (I = F × Δt). It equals the change in linear momentum of the object (I = ΔP = mvf − mvi). This relationship is covered in short question 3.9 and is important for board exams.

Q6: At what angle is the range of a projectile maximum?
The range of a projectile is maximum when it is thrown at an angle of 45° with the horizontal. At this angle, sin 2θ = sin 90° = 1, which gives the maximum value of range Rmax = vᵢ²/g. This is proved in Chapter 3 short question 3.12.

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