Angular Acceleration – Class 11 | Chapter – 7 | Physics Short Notes Series PDF for NEET & JEE

Angular Acceleration: Angular acceleration is a measure of how quickly an object is changing its angular velocity. It is denoted by the symbol α (alpha) and is expressed in units of radians per second squared (rad/s2). Angular acceleration plays an important role in rotational motion and can be used to calculate other rotational quantities such as torque and angular momentum. It can also be used to describe the motion of objects that are not rotating in a perfect circular path, such as objects undergoing general rotational motion or objects experiencing precession or nutation.

Formula of Angular Acceleration

The formula for angular acceleration is:

α = Δω / Δt


  • Δω is the change in angular velocity
  • Δt is the time taken for the change to occur.

Just like linear acceleration, angular acceleration can be either positive or negative depending on whether the object is accelerating in the clockwise or counterclockwise direction. If an object is rotating in a circular path and its angular acceleration is constant, then its rotational motion can be described by the following equation:

ω = ω0 + αt


  • ω is the final angular velocity,
  • ω0 is the initial angular velocity,
  • α is the angular acceleration, and
  • t is the time taken for the change in velocity to occur.

Importance of Angular Acceleration

Angular acceleration is an important concept in the study of rotational motion and has several important applications in physics and engineering. Some of the key importance of angular acceleration are:

  • Describing rotational motion: Angular acceleration is a key parameter used to describe the rotational motion of objects. It is used to describe how quickly an object is changing its angular velocity, which is essential for predicting the behavior of rotating systems.
  • Calculating torque: Torque is a measure of the turning force applied to an object and is proportional to the product of the force and the distance from the axis of rotation. Angular acceleration is used to calculate torque, which is an important parameter in many applications including engines, motors, and turbines.
  • Understanding angular momentum: Angular acceleration plays a key role in determining the angular momentum of a rotating object. Angular momentum is a measure of the tendency of a rotating object to continue rotating and is essential for understanding the behavior of rotating systems.
  • Predicting rotational stability: The angular acceleration of a rotating object is related to its moment of inertia, which is a measure of an object’s resistance to changes in its rotational motion. This relationship is important for predicting the rotational stability of objects and systems.
  • Engineering applications: Angular acceleration is important in many engineering applications, including the design of rotating machinery such as engines, turbines, and flywheels. It is also used in robotics and other automated systems that involve rotational motion.

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By Team Learning Mantras