Class 9th Physics Formula Sheet – Quick Revision

Chapter 1: Motion

Brief: Motion describes how objects move – speed, velocity, acceleration, and equations of motion.

Formulas & Explanations:

1. Speed – how fast an object moves:

• $s\; =\; speed,\; d$ = distance, $t$ = time.

2. Velocity – speed with direction:

3. Acceleration – change of velocity per unit time:

4. Equations of uniformly accelerated motion:

• 1st:

• 2nd:

• 3rd:

5. Motion under gravity (replace a with g):

• Downwards:

• Upwards:

---

Chapter 2: Force

Brief: Force makes objects move, stop, or change direction.

Formulas & Explanations:

1. Newton’s 2nd Law:

• Force is mass × acceleration.

 2. Momentum:

• Product of mass & velocity.

 3. Impulse:

• Sudden push/pull = change in momentum.

 4. Law of Conservation of Momentum:

• m1​,m2​

  • Mass of two objects (before and after collision).

  • Example: Car A and Car B colliding.

• v1,v2​

  • Initial velocities of the objects (before collision).

• v1′,v2′​

  • Final velocities of the objects (after collision).

  • The prime (′) indicates after the event.

---

Chapter 3: Gravitation

Brief: Explains how all objects attract each other.

Formulas & Explanations:

 1. Universal Gravitation:

• Force of attraction between two masses.

 2. Acceleration due to gravity:

• Value of g = 9.8 m/s² on Earth.

 3. Orbital Velocity of satellite:

 6. Centripetal Force:

• Keeps body in circular path.