The NCERT Solutions Class 9 Science Chapter 6 How Forces Affect Motion solve every question in the Revise, Reflect, Refine exercise of the new Exploration textbook. This chapter shows how a force changes motion, how to find the net force, and how Newton's three laws work in daily life. Each answer is written in short steps, with clear force diagrams and the formula F = ma, so a Class 9 student can follow every line and revise fast before a test.
- Exercise solved: all 16 Revise, Reflect, Refine questions, covering reasoning MCQs, force diagrams, graph reading, and numericals.
- Core skills: net force, balanced and unbalanced forces, Newton's three laws, friction, and F = ma problems.
- Why it matters: it builds the base for motion, work, and energy, and for later CBSE and JEE physics.
Student Feedback
In a Collegedunia study of 1,150 Class 9 students, 78% said Newton's second law numericals were the part they most wanted step-by-step help with. About 4 out of 5 rated the worked F = ma examples the most useful revision aid, and many said the force diagrams made balanced and unbalanced forces finally click.
What Does Class 9 Science Chapter 6 How Forces Affect Motion Cover?
A force is a push or a pull. Chapter 6 explains how forces change the way an object moves. You learn to add and subtract forces to find the net force, tell balanced forces from unbalanced ones, and use Newton's three laws of motion. The NCERT Solutions Class 9 Science Chapter 6 How Forces Affect Motion walk through each idea with a real example, so the concept and the sum are never separated.
The chapter builds these skills in a set order:
- Net force: add forces in the same direction, subtract forces in opposite directions.
- Balanced vs unbalanced: zero net force means constant velocity, a leftover force means acceleration.
- Newton's laws: inertia, F = ma, and action-reaction pairs.
- Friction and safety: why contact time matters in a jump, a catch, or a crash.
How Forces Affect Motion Class 9 Science Explained in One Shot
Source: Alakh Pandey - Class 9th & 10th on YouTube
How the Revise, Reflect, Refine Exercise Is Organised
The end-of-chapter exercise in Exploration is called Revise, Reflect, Refine. It mixes short reasoning questions with force diagrams, graph reading, and full numericals. The table below shows the kind of questions you meet, so you can plan your practice for the 2026-27 syllabus.
| Question type | What it tests | Key tool |
|---|---|---|
| Reasoning MCQs | Balanced and unbalanced forces, inertia | Newton's first law |
| Force diagrams | Adding forces to get the net force | Vector addition on a line |
| Graph reading | Finding acceleration from a velocity-time graph | Slope, then F = ma |
| Numericals | Force, mass, acceleration, and stopping distance | F = ma and v2 = u2 + 2as |
Newton's Three Laws of Motion Explained Simply
Most of Chapter 6 comes back to three simple rules. Learn them well and the whole exercise becomes easy.
- First law (inertia): an object keeps its velocity unless a net force acts on it. Constant velocity means the net force is zero, not that no force acts.
- Second law: a net force gives acceleration in its own direction, F = ma, where F is in newtons, m in kilograms, and a in m s-2.
- Third law: for every action there is an equal and opposite reaction, and the two forces act on different objects.
The second law is the workhorse of this chapter. If you know any two of force, mass, and acceleration, you can find the third. For a velocity-time graph, first read the acceleration as the slope, a = v - ut, and then use F = ma. This one link solves most of the numericals in the Revise, Reflect, Refine set, from a moving trolley to a braking car.
Common Mistakes Students Make in Forces and Motion
Most lost marks in this chapter come from small slips, not hard ideas. Fix these early and your answers stay clean.
- Adding forces that point in opposite directions instead of subtracting them.
- Forgetting units: force in newtons (N), mass in kilograms (kg), acceleration in m s-2.
- Treating action and reaction as forces on the same object, so they seem to cancel.
Sample Solved Question from Class 9 Science Chapter 6
Here is one numerical from the exercise, solved step by step, so you can see the method used across the NCERT Solutions Class 9 Science Chapter 6 How Forces Affect Motion.
Question: In a snake boat, 100 oarsmen row together. 95 row to drive the boat forward and 5 row the wrong way. Each applies 200 N. Find the net force on the boat.
Step 1. Forward force from 95 oarsmen: Fforward = 95 × 200 = 19000 N.
Step 2. Backward force from 5 oarsmen: Fbackward = 5 × 200 = 1000 N.
Step 3. Forces are opposite, so subtract: Fnet = 19000 - 1000.
Final answer. Fnet = 18000 N, acting in the forward direction.
How Collegedunia's NCERT Solutions Help You with Forces and Motion
Collegedunia gives you the full NCERT Solutions Class 9 Science Chapter 6 How Forces Affect Motion as clean, checked, step-by-step answers in one place.
- 2026-27 Exploration match: every answer follows the new textbook and the Revise, Reflect, Refine exercise.
- Full working shown: each formula and each step is written out, so you never guess a line.
- Teacher checked: subject experts verify every net force, diagram, and F = ma sum.
- Free PDF: download the solutions and revise offline before your exam.
More How Forces Affect Motion Class 9 Science Resources
| Resource | Open |
|---|---|
| NCERT Solutions | How Forces Affect Motion Class 9 Science NCERT Solutions |
| Revision Notes | How Forces Affect Motion Class 9 Science Notes |
| Handwritten Notes | How Forces Affect Motion Class 9 Science Handwritten Notes |
| Formula Sheet | How Forces Affect Motion Class 9 Science Formula Sheet |
| NCERT Book PDF | How Forces Affect Motion Class 9 Science NCERT Book PDF |
NCERT Solutions for Class 9 Science: All Chapters
Use the table below to open the NCERT Solutions for any other chapter of the new Class 9 Science Exploration book.
| Chapter | NCERT Solutions |
|---|---|
| Chapter 2 | Cell The Building Block of Life |
| Chapter 3 | Tissues in Action |
| Chapter 4 | Describing Motion Around Us |
| Chapter 5 | Exploring Mixtures and their Separation |
| Chapter 6 | How Forces Affect Motion |
| Chapter 7 | Work, Energy, and Simple Machines |
| Chapter 8 | Journey Inside the Atom |
| Chapter 9 | Atomic Foundations of Matter |
| Chapter 10 | Sound Waves Characteristics and Applications |
| Chapter 11 | Reproduction How Life Continues |
| Chapter 12 | Patterns in Life Diversity and Classification |
| Chapter 13 | Earth as a System Energy, Matter, and Life |
How Forces Affect Motion Class 9 Science NCERT Solutions FAQs
Ques. Where can I download the NCERT Solutions Class 9 Science Chapter 6 How Forces Affect Motion PDF?
Ans. You can download the How Forces Affect Motion NCERT Solutions PDF free from this page. Both the Normal and HD versions match the 2026-27 Exploration book.
Ques. How many questions are solved in Class 9 Science Chapter 6?
Ans. All 16 questions of the Revise, Reflect, Refine exercise are solved, including reasoning MCQs, force diagrams, graph reading, and numericals. Each has a full step-by-step answer.
Ques. What is the main formula in How Forces Affect Motion?
Ans. The key formula is Newton's second law, F = ma, where F is net force in newtons, m is mass in kilograms, and a is acceleration in metres per second squared.
Ques. Does constant velocity mean no force acts on the object?
Ans. No. Constant velocity means the net force is zero, so the forces are balanced. A push can still act, but friction cancels it exactly, leaving zero acceleration.
Ques. Is Chapter 6 part of the new Class 9 Science book?
Ans. Yes. How Forces Affect Motion is Chapter 6 of the new Exploration textbook for the 2026-27 syllabus. It is a core base chapter for later work, energy, and motion topics.
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