How Forces Affect Motion — Class 9 Science NCERT Solutions (Free)

Free step-by-step NCERT solutions for Class 9 Science chapter "How Forces Affect Motion" — 8 important questions with detailed answers for CBSE board exam preparation.

✓ 100% Free ✓ No Login Needed ✓ NCERT / CBSE Aligned ✓ Download as PDF

TL;DR: Free step-by-step NCERT solutions for Class 9 Science chapter "How Forces Affect Motion" — 8 important questions with detailed answers for CBSE board…

Written & reviewed by the Syllab.in Academic Team (CBSE/NCERT subject experts) · Updated Jul 23, 2026

🤖 Stuck on any question? Ask Syllab's free AI Tutor for a step-by-step explanation — instant, unlimited, no login.

Key Questions Covered:

State Newton's First Law of Motion.
What is inertia? Give an example.
State Newton's Second Law of Motion and write its formula.
A 2 kg mass experiences a force of 10 N. Find its acceleration.
State Newton's Third Law of Motion.
Define momentum and write its formula.
+ 2 more questions in the full chapter

Solutions Summary:

Question	Status
State Newton's First Law of Motion.	✓ Solved
What is inertia? Give an example.	✓ Solved
State Newton's Second Law of Motion and write its formula.	✓ Solved
A 2 kg mass experiences a force of 10 N. Find its acceler…	✓ Solved
State Newton's Third Law of Motion.	✓ Solved
Define momentum and write its formula.	✓ Solved

Showing 6 of 8 questions

Q1: State Newton's First Law of Motion.

An object at rest remains at rest, and an object in motion continues moving in a straight line at constant velocity unless acted upon by an external force. This is the law of inertia.

Q2: What is inertia? Give an example.

Inertia is the tendency of an object to resist changes in its state of motion or rest. A car suddenly stopping causes passengers to lurch forward (they tend to continue moving). Heavier objects have greater inertia.

Q3: State Newton's Second Law of Motion and write its formula.

The acceleration of an object is directly proportional to the applied force and inversely proportional to its mass. Formula: F = ma Where F = force (N), m = mass (kg), a = acceleration (m/s²)

Q4: A 2 kg mass experiences a force of 10 N. Find its acceleration.

Step 1: m = 2 kg, F = 10 N Step 2: F = ma Step 3: a = F/m = 10/2 = 5 m/s²

Q5: State Newton's Third Law of Motion.

For every action, there is an equal and opposite reaction. When object A exerts a force on object B, object B exerts an equal and opposite force on object A. Forces always occur in pairs.

Q6: Define momentum and write its formula.

Momentum is the product of mass and velocity of an object. Formula: p = mv Where p = momentum (kg m/s), m = mass (kg), v = velocity (m/s) It is a vector quantity with direction.

Showing 6 of 8 questions. Visit the full page for complete solutions.