ROTATIONAL MOTION –
CLASS 11 (FULL 15-PAGE
NOTES)
“Deep Concepts • Detailed Explanations • Exam-Focused
Examples”
Created For: Smart Students Who Want to Master Physics
, 1. Introduction to Rotational Motion
In physics, motion can be of two major types: translational and rotational.
Translational motion occurs when every particle of a body moves the same
distance in the same time. Rotational motion occurs when a body turns about a
fixed axis.
In rotational motion, different points of the body describe circular paths but with the
same angular displacement.
This chapter helps students understand real-life motions such as wheels, fans,
gears, Earth’s rotation, machinery, turbines, roller bearings, etc.
**Example:**
When a ceiling fan rotates, every point on the blade moves in a circle with the
same angular speed. However, the linear speed of a point near the edge is greater
than the point near the center.
2. Rigid Body and Rotational Variables
A rigid body is an idealized concept in which the distance between any two
particles remains constant even when forces are applied. Although no perfect rigid
body exists, many solid objects behave almost like rigid bodies.
Key rotational variables:
- **Angular Displacement (θ)**
- **Angular Velocity (ω)**
- **Angular Acceleration (α)**
**Example:**
A wheel rotating from rest reaches 30 rad/s in 5 seconds.
Angular acceleration = ω/t = 30/5 = **6 rad/s²**
3. Relation Between Linear and Angular Variables
CLASS 11 (FULL 15-PAGE
NOTES)
“Deep Concepts • Detailed Explanations • Exam-Focused
Examples”
Created For: Smart Students Who Want to Master Physics
, 1. Introduction to Rotational Motion
In physics, motion can be of two major types: translational and rotational.
Translational motion occurs when every particle of a body moves the same
distance in the same time. Rotational motion occurs when a body turns about a
fixed axis.
In rotational motion, different points of the body describe circular paths but with the
same angular displacement.
This chapter helps students understand real-life motions such as wheels, fans,
gears, Earth’s rotation, machinery, turbines, roller bearings, etc.
**Example:**
When a ceiling fan rotates, every point on the blade moves in a circle with the
same angular speed. However, the linear speed of a point near the edge is greater
than the point near the center.
2. Rigid Body and Rotational Variables
A rigid body is an idealized concept in which the distance between any two
particles remains constant even when forces are applied. Although no perfect rigid
body exists, many solid objects behave almost like rigid bodies.
Key rotational variables:
- **Angular Displacement (θ)**
- **Angular Velocity (ω)**
- **Angular Acceleration (α)**
**Example:**
A wheel rotating from rest reaches 30 rad/s in 5 seconds.
Angular acceleration = ω/t = 30/5 = **6 rad/s²**
3. Relation Between Linear and Angular Variables
