SCIENCE IMPORTANT FORMULAE CLASS - 9
Important Formulae for class 9 science
Updated for new syllabus - 2026
Class 9 science Important Formulae
The Important Science Formulae section at Saraswat Academy provides a complete collection of chapter-wise scientific formulas based on the latest CBSE Syllabus 2026–27. These formulas are carefully selected from the NCERT textbooks and presented in a simple, easy-to-understand format for quick learning and revision. They help students strengthen their conceptual understanding, solve numerical problems accurately, and improve problem-solving speed in Physics, Chemistry, and other formula-based topics. Regular practice of these formulas is essential for homework, class tests, unit tests, practical examinations, half-yearly examinations, annual examinations, and CBSE board examinations. This page serves as a quick revision resource, enabling students to recall important formulas confidently and perform better in both school and competitive examinations.
Regular revision of scientific formulas helps students strengthen conceptual understanding, improve numerical problem-solving skills, and reduce errors in calculations during examinations. Whether you are preparing for school assessments, practical examinations, or CBSE board exams, these chapter-wise science formula sheets provide a quick and effective revision resource. Students are encouraged to practise these formulas alongside NCERT questions, exemplar problems, practical-based questions, competency-based questions, and previous years' board questions to develop scientific reasoning, enhance accuracy, and achieve excellent marks in Science.
Important Formulae: Science Class - 9
Chapter - 6
Important Formulae - Chapter 6: How Forces Affect Motion
1. Net Force (Forces in the Same Direction)
Formula
Net Force = F₁ + F₂ + F₃ + ...
When all forces act in the same direction, their magnitudes are added.
2. Net Force (Opposite Directions)
Formula
Net Force = Larger Force − Smaller Force
Direction of Net Force = Direction of the Larger Force
3. Second Equation of Motion
Formula
s = ut + ½at²
Special Case (Object starts from rest)
u = 0
s = ½at²
4. Ratio of Accelerations (Activity 6.3)
a₁ / a₂ = T₂² / T₁²
This relation is obtained when the object travels the same distance in both cases.
5. Newton's Second Law
Main Formula
F = ma
Alternative Form
a = F / m
6. Weight (Gravitational Force)
F = mg
where
- F = Weight (Force)
- m = Mass
- g = Acceleration due to gravity
7. Acceleration due to Gravity
g = 9.8 m/s²
For quick calculations,
g ≈ 10 m/s²
8. Definition of One Newton
1 N = 1 kg × 1 m/s²
or
1 N = 1 kg·m/s²
9. SI Unit Relationship
| Physical Quantity | SI Unit |
|---|---|
| Force | Newton (N) |
| Mass | Kilogram (kg) |
| Acceleration | m/s² |
| Weight | Newton (N) |
10. Momentum (Conceptual Formula)
Momentum = Mass × Velocity
p = mv
(Direction of momentum is the same as the direction of velocity.)
Important Standard Values
- 1 Newton = Force required to produce an acceleration of 1 m/s² in a body of mass 1 kg.
- Acceleration due to gravity near Earth's surface = 9.8 m/s².
- Approximate value for numerical calculations = 10 m/s².
- A 100 g object has a weight of approximately 1 N.
- The SI symbol of Newton is N (capital letter).
- The word newton is written in lowercase when written in full.
Quick Revision Formulae
- Net Force (same direction) = F₁ + F₂ + ...
- Net Force (opposite directions) = Larger Force − Smaller Force
- s = ut + ½at²
- s = ½at² (when u = 0)
- a₁/a₂ = T₂²/T₁²
- F = ma
- a = F/m
- F = mg
- g = 9.8 m/s² ≈ 10 m/s²
- Momentum = mv
- 1 N = 1 kg·m/s²