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What is Angular Acceleration in Physics?

What is Angular Acceleration in Physics?

Angular acceleration in Physics refers to the rate at which an object’s angular velocity changes with respect to time. Angular velocity represents the object’s rotational speed and direction. When an object experiences angular acceleration, it means its rotational speed is changing, either by increasing or decreasing.

What is Angular Acceleration in Physics
What is Angular Acceleration in Physics

Angular Acceleration Formula

The formula to calculate angular acceleration is given by:

α = (Δω) / (Δt)


  • α represents angular acceleration,
  • Δω denotes the change in angular velocity, and
  • Δt represents the change in time.


Angular acceleration is a fundamental concept in physics and engineering that relates to the rate at which an object’s angular velocity changes over time. It plays a crucial role in understanding rotational motion, whether it’s the movement of celestial bodies, machinery components, or sports equipment. In this article, we will delve into the concept of angular acceleration, explore its applications, and learn how to calculate it.

Units of Angular Acceleration

Angular acceleration is measured in units of radians per second squared (rad/s²) or degrees per second squared (°/s²). These units convey the change in angular velocity per unit time.

Understanding Angular Acceleration

To grasp angular acceleration better, let’s consider a spinning top. Initially, the top is at rest, but as you apply a force, it starts rotating. The initial angular velocity is zero, and as the top gains rotational speed, the angular velocity increases. This change in angular velocity over time is angular acceleration.

Angular Acceleration vs. Linear Acceleration

Angular acceleration should not be confused with linear acceleration. Linear acceleration relates to the change in linear velocity, while angular acceleration focuses on the change in angular velocity. While linear acceleration deals with straight-line motion, angular acceleration is specific to rotational motion.

Calculating Angular Acceleration

To calculate angular acceleration, you need to determine the change in angular velocity and the time taken for that change. Let’s say an object initially rotates at an angular velocity ω₁ and after a certain time Δt, its angular velocity becomes ω₂. The angular acceleration (α) can be calculated using the formula:

α = (ω₂ – ω₁) / Δt

Factors Affecting Angular Acceleration

Several factors influence angular acceleration, including the applied torque or force, the moment of inertia, and the distribution of mass within the rotating object. Torque is responsible for changing an object’s angular momentum and, consequently, its angular acceleration.


Angular acceleration finds applications in various fields. These fields include physics, engineering, and sports. Some notable applications include:

  1. Physics: Angular acceleration helps explain the motion of planets, the rotation of satellites, and the behaviour of objects in space.
  2. Engineering: Understanding angular acceleration is important in designing machinery, such as engines, turbines, and rotating components.
  3. Sports: Angular acceleration plays a role in sports like gymnastics, figure skating, and diving, where rotational movements are key to performance.

Examples of Angular Acceleration

  1. A car moving along a curved road experiences angular acceleration as it changes its direction. When the driver steers the wheel to the left or right, the car’s tires exert a torque, resulting in a change in angular velocity and acceleration.
  2. A spinning ice skater performing a pirouette demonstrates angular acceleration. As the skater pulls their arms closer to their body, their moment of inertia decreases, causing an increase in angular velocity and acceleration.

Angular Acceleration in Rotational Motion

In rotational motion, angular acceleration plays a vital role. It describes how quickly an object’s rotational speed changes and provides insights into the dynamics of rotating systems. Understanding angular acceleration enables us to analyze the behaviour of objects such as wheels, propellers, and gears.

Angular Acceleration in Physics

Angular acceleration is a very important concept in rotational dynamics. It helps explain the principles behind rotational motion, including torque, angular momentum, and moment of inertia. By understanding angular acceleration, physicists can accurately predict and describe the behaviour of rotating systems.

Angular Acceleration in Engineering

Engineers heavily rely on angular acceleration in various fields. For instance, in the design of engines, turbines, and flywheels, understanding angular acceleration is crucial to ensure the smooth operation and efficiency of rotating components. Engineers also consider angular acceleration when designing machinery that involves gears, pulleys, and rotating parts.

Angular Acceleration in Sports

Sports that involve rotational movements, such as gymnastics, figure skating, and diving, rely on angular acceleration. Athletes utilize angular acceleration to perform complex manoeuvres, spins, and flips. By manipulating their body position and distribution of mass, they can increase or decrease their rotational speed to achieve desired movements and maximize their performance.


Angular acceleration is a fundamental concept that describes the rate at which an object’s angular velocity changes over time. It plays a crucial role in understanding rotational motion in various fields, including physics, engineering, and sports. By grasping the concept of angular acceleration and its applications, we can gain valuable insights into the behaviour of rotating objects and systems.

Frequently Asked Questions

  1. Is angular acceleration the same as angular velocity? No, angular acceleration and angular velocity are different concepts. Angular acceleration represents the rate of change of angular velocity, while angular velocity refers to the rotational speed and direction of an object.
  2. Can angular acceleration be negative? Yes, angular acceleration can be positive or negative. A positive angular acceleration indicates an increase in rotational speed, while a negative angular acceleration signifies a decrease in rotational speed.
  3. How is angular acceleration related to torque? Torque is responsible for changing an object’s angular momentum, which in turn affects its angular acceleration. A larger torque results in a larger angular acceleration, while a smaller torque leads to a smaller angular acceleration.
  4. Can angular acceleration affect linear motion? Angular acceleration and linear motion are distinct concepts. While angular acceleration relates to changes in rotational speed, linear motion deals with changes in straight-line velocity. However, in some cases, angular acceleration can indirectly affect linear motion through the influence of rotational forces.
  5. What are some real-life examples of angular acceleration? Real-life examples of angular acceleration include the spinning of a merry-go-round, the rotation of a bicycle wheel, and the swinging of a pendulum. These scenarios involve objects experiencing changes in their rotational speed over time.

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Acceleration Formula


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