Laws of Motion ചലനനിയമങ്ങൾ
Why does the rope in an Onam tug of war move towards one team? Why do you fall forward when a KSRTC bus brakes suddenly? Why does a cricketer pull the hands back while catching a fast ball? How does a rocket leave Sriharikota with nothing to push against? Isaac Newton answered all of these with three short laws of motion. This interactive, animated self-study guide starts with the basics from earlier classes (forces as arrows, speed, velocity, acceleration, graphs, mass and friction). It then explains every idea of the chapter with Kerala examples: resultant force, inertia, momentum, F = ma, impulse, action and reaction. Every textbook question is solved in exam layout, and the guide ends with a revision sheet and a model test with a fully solved paper.
The chapter in one picture
Left: the two red arrows are drawn to scale. While the pulls are equal (350 N each) the forces are balanced (സന്തുലിതബലങ്ങൾ) and the rope stays still. When the right team pulls 450 N against 350 N, the forces are unbalanced (അസന്തുലിതബലങ്ങൾ). The resultant force (സഫലബലം, purple) of 100 N points right, and the rope starts moving right, faster and faster. Right: the rocket pushes hot gases down (action), and the gases push the rocket up (reaction, the thrust). That is Newton's third law, which you will meet on page 12.
How to use this guide
🎬 Watch the animations
Ropes move, carts speed up, balls collide and rockets lift off, one step at a time. Press Next ▶ or ▶▶ Auto play.
🧪 Do the virtual experiments
Move the sliders to change a force, a mass or a speed. The figure, the arrows and the numbers all update together, exactly as the physics says.
✍️ Try before you see
Every numerical is laid out the exam way: Given → Formula → Substitution → Answer with unit. Use 💡 Show a hint first and work in your notebook. Then open ✅ Show final answer.
📖 Textbook words
Purple മലയാളം words are the exact terms used in your textbook (pages 53–72), so you can match this guide with your book.
Learning path
Follow the pages in order. If you already remember forces, speed, velocity, acceleration, the equations of motion and graphs well, you can skim pages 1–4. Still try their quizzes, because the chapter uses all of these all the time.
Quick glossary (Malayalam ↔ English)
| Textbook term | English | Meaning |
|---|---|---|
| ചലനനിയമങ്ങൾ | Laws of motion | Newton's three rules that tell how forces change motion (the chapter title) |
| ബലം | Force | A push or a pull; measured in newtons (N); it has a size and a direction |
| സഫലബലം / പരിണതബലം | Resultant force (net force) | The total effect of all the forces acting on an object at the same time |
| സന്തുലിതബലങ്ങൾ | Balanced forces | Forces whose resultant is zero; they cannot change the state of rest or motion |
| അസന്തുലിതബലങ്ങൾ | Unbalanced forces | Forces whose resultant is not zero; they change speed or direction |
| ബാഹ്യബലം · ആന്തരികബലം | External force · internal force | A force from outside the object · a force from inside it (pushing an autorickshaw while sitting in it) |
| സന്തുലിത ബാഹ്യബലം / അസന്തുലിത ബാഹ്യബലം | Balanced / unbalanced external force | Only an unbalanced external force can change an object's state of rest or motion |
| നിശ്ചലാവസ്ഥ · ചലനാവസ്ഥ | State of rest · state of motion | Not moving · moving |
| ചലനദിശ | Direction of motion | The way the object is moving |
| വേഗം · പ്രവേഗം | Speed · velocity | Distance per second (m/s) · speed in a stated direction |
| ആദ്യപ്രവേഗം / അന്ത്യപ്രവേഗം | Initial / final velocity | u (at the start) and v (at the end) |
| ത്വരണം · മന്ദീകരണം | Acceleration · retardation | Change in velocity per second, a = (v − u)/t, in m/s² · a negative acceleration (slowing down) |
| സമപ്രവേഗം · സമത്വരണം | Uniform velocity · uniform acceleration | Same speed and same direction · velocity changing by the same amount every second |
| സമചലനം · നേർരേഖയിലുള്ള സമചലനം | Uniform motion · uniform motion in a straight line | Equal distances in equal times · the same, along a straight line |
| സ്ഥാനാന്തരം | Displacement | Straight-line distance from the start to the end, with direction |
| ഘർഷണം | Friction | The force between surfaces that opposes motion; it makes rolling balls stop |
| ഗലീലിയോയുടെ നിരീക്ഷണങ്ങൾ | Galileo's observations | The rolling-ball experiments on slopes that led to the idea of inertia |
| ന്യൂട്ടന്റെ ഒന്നാം ചലനനിയമം | Newton's first law of motion | An object stays at rest or in uniform motion in a straight line unless an unbalanced external force acts on it |
| ന്യൂട്ടന്റെ രണ്ടാം ചലനനിയമം | Newton's second law of motion | Rate of change of momentum ∝ unbalanced external force; F = ma |
| ന്യൂട്ടന്റെ മൂന്നാം ചലനനിയമം | Newton's third law of motion | For every action there is an equal and opposite reaction |
| ജഡത്വം | Inertia | The tendency of an object to stay in its state of rest or motion; more mass, more inertia |
| നിശ്ചലജഡത്വം · ചലനജഡത്വം | Inertia of rest · inertia of motion | Passengers fall back when a bus starts · fall forward when it stops |
| മാസ് | Mass | The quantity of matter in an object, in kilograms (kg) |
| മൊമെന്റം | Momentum | p = mv, mass × velocity, in kg m/s; a vector |
| ആദ്യമൊമെന്റം / അന്ത്യമൊമെന്റം | Initial / final momentum | mu and mv |
| മൊമെന്റവ്യത്യാസം · മൊമെന്റവ്യത്യാസനിരക്ക് | Change in momentum · rate of change of momentum | mv − mu (kg m/s) · (mv − mu)/t (kg m/s², which is the same as N) |
| സദിശ അളവ് | Vector quantity | A quantity with both size and direction: displacement, velocity, force, momentum |
| ന്യൂട്ടൻസ് ക്രാഡിൽ | Newton's cradle | A row of hanging steel balls that passes momentum from one end to the other |
| ആവേഗബലം · ബലത്തിന്റെ ആവേഗം | Impulsive force · impulse of a force | A large force for a very short time (bat on ball) · I = F × t, in N s |
| ആവേഗമൊമെന്റതത്വം | Impulse–momentum principle | Impulse = change in momentum: Ft = mv − mu |
| പ്രതിബലം · ബലവും പ്രതിബലവും | Reaction · action and reaction | The equal and opposite force; the pair acts on two different objects at the same instant |
| സ്ഥിരസംഖ്യ · നേർ അനുപാതം | Constant · direct proportion | A fixed number (k in F = kma) · one doubles when the other doubles |
| ഗ്രാഫ് | Graph | A picture of how one quantity changes with another (distance–time, velocity–time) |
| പ്രവർത്തനം · സയൻസ് ഡയറി | Activity · science diary | Things to do, and the notebook where you write what you found |
| വിലയിരുത്താം · തുടർപ്രവർത്തനങ്ങൾ | Let us assess · extended activities | The end-of-chapter questions and projects (solved on pages 13–14) |
🌐 Explore online (optional)
Everything in this guide works offline: each page is a single file with no internet needed. Some pages also have blue “🌐 Explore online” boxes. They link to free simulations and videos from PhET, NASA, ISRO and YouTube. Those links need internet and open in a new tab. All of them are collected in the resources hub on page 15.
- ▶️ Class 9 Physics | Chapter 3 | Laws of Motion | ചലനനിയമങ്ങൾ | Full Chapter in 10 Min YouTube – Exam Winner Class 9 (private tuition channel) · 12:35
Quick Malayalam revision of the whole chapter. - ▶️ Class 9 physics | Laws of Motion | ചലനനിയമങ്ങൾ | Chapter 3 YouTube – Eduport Class 9 (private tuition channel) · 54:19
Detailed Malayalam class covering the chapter. - ▶️ Class 9 Physics | Chapter: 3 | Laws of Motion / ചലന നിയമങ്ങൾ | Part: 1 YouTube – Xylem class 9 (private tuition channel) · 1:10:25
Long Malayalam lecture, part 1 of the chapter. - ▶️ Newton's 3 Laws, with a bicycle - Joshua Manley YouTube – TED-Ed · 3:33
All three laws explained with a bicycle ride.
Made for self-learning. Works offline – every page is a single file. Study material prepared by Claude for Madhu's family study folder, October 2026.