# Angular velocity: definition, formula and example exercises

Angular velocity is a fundamental concept in physics that plays a crucial role in understanding and describing rotary motion.

In this article, we will explain what angular velocity is, how it is calculated using simple example exercises, and some of its real-world applications.

## What is angular velocity?

Angular velocity is a measure of how quickly an object rotates around an axis or point of rotation. In other words, it is the rate of change of angle as an object rotates. It is generally expressed in radians per second (rad/s) in the International System of Units (SI).

To better understand this concept, let's imagine a wheel rotating on its axis. Angular velocity tells us how many radians of angle the wheel travels in one second. If a wheel completes one revolution (360 degrees or 2π radians) in one second, its angular velocity would be 2π rad/s. In short, angular velocity is a measure of how fast an object rotates in terms of angles per unit time.

## Formula and calculation of angular velocity

The angular velocity is calculated using the following formula:

ω=Δθ / Δt

Where:

• Δθ is the change in angle in radians.

• Δt is the change in time in seconds (s).

## Solved example exercises

To illustrate this calculation, let's consider the following example exercises:

### Example exercise 1

An exercise bike has a wheel that rotates. If the wheel completes one revolution (2π radians) in 4 seconds, calculate the angular velocity.

Solution:

In this case, the angular velocity of the bicycle wheel is π/2 rad/s.

### Example exercise 2

Suppose a fan stops after rotating 3 revolutions (3 × 2π radians) in 6 seconds. Calculate the initial angular velocity

Solution:

In this case, the initial angular velocity of the fan is π rad/s.

## Uses and applications

Angular velocity has a wide range of applications in physics and engineering, and is fundamental to understanding the motion of rotating objects.

Below are some of the most common applications:

### 1. Mechanical engineering

In mechanical engineering, angular velocity is essential for the design and analysis of machines and mechanisms that involve rotary motion such as gearboxes and gears.

For example, in engine and transmission construction, it is crucial to calculate angular velocity to ensure efficient and safe operation.

### 2. Astronomy

In astronomy, angular velocity is used to describe the motion of celestial objects, such as planets, stars, and galaxies. It allows astronomers to calculate the rotation speed of planets and the spin speed of stars, which in turn helps to better understand the cosmos.

For example, the angular velocity of Earth's rotation is approximately 7.29 x 10-5 rad/s, which determines the length of a day.

### 3. Particle physics

In quantum physics, angular velocity is relevant in the study of subatomic particles such as electrons and quarks.

Experiments in particle accelerators often involve particles moving at extremely high angular velocities, requiring precise measurements of angular velocity.

For example, at the Large Hadron Collider (LHC), particles are accelerated to speeds close to the speed of light, and their angular velocity is essential for trajectory calculations.

In navigation systems such as GPS, it is used to determine the orientation and direction of movement of a device. This allows GPS receivers to calculate the position and speed of a moving object, which is essential for accurate navigation.

For example, when you use a GPS device in your car, angular velocity is used to determine the direction you are moving and how much you have turned.

### 5. Thermal power plants

In a thermal power plant, for example a nuclear power plant, the heat source generates steam to drive a steam turbine. The angular speed of the turbine determines the efficiency of converting thermal energy into electricity: higher angular speed means greater energy production.

### 6. Wind energy

In a wind turbine, the speed at which the blades rotate is crucial to obtain a balance between electrical production and safety. At a certain wind speed, the turbines must stop because they could not withstand the centripetal force that would be generated by too high an angular velocity.

### 7. Computer animation

In the film and video game industry, angular velocity is used in computer animation to simulate the realistic movement of rotating objects. This calculation allows for convincing visual effects and exciting action scenes.

For example, in a science fiction movie, angular velocity is used to simulate the rotation of planets and stars in outer space.

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Publication Date: September 21, 2023
Last Revision: September 21, 2023