Calculate angular momentum, moment of inertia, or angular velocity for rotating systems
L = I × ω
Where: L = angular momentum, I = moment of inertia, ω = angular velocity
Measure of rotational motion (kg·m²/s)
Resistance to rotational motion (kg·m²)
Rate of rotation (rad/s)
Choose calculation type and enter the required parameters.
Law of Conservation:
L_initial = L_final
Angular momentum is conserved when no external torque acts on the system.
Angular momentum is a fundamental concept in physics that describes the rotational motion of objects. Unlike linear momentum, which deals with straight-line motion, angular momentum quantifies how much an object is rotating and its tendency to keep rotating. Our Angular Momentum Calculator helps students, engineers, and physicists calculate angular momentum, moment of inertia, and angular velocity for various rotating systems. This tool is essential for understanding rotational dynamics, from spinning tops to planetary orbits, making complex physics calculations accessible and intuitive.
The primary formula for angular momentum is:
L = I × ω Where: L = Angular momentum (kg·m²/s) I = Moment of inertia (kg·m²) ω = Angular velocity (rad/s) For moment of inertia calculations, different shapes have specific formulas: - Solid sphere about diameter: I = (2/5)MR² - Hollow sphere about diameter: I = (2/3)MR² - Solid cylinder about central axis: I = (1/2)MR² - Thin rod about center perpendicular to length: I = (1/12)ML² - Hoop or thin cylindrical shell: I = MR² Where M is mass and R/L is radius or length.
Angular momentum works in 1D, 2D, and 3D rotational systems, but the calculator focuses on the fundamental relationship between the three quantities.
The moment of inertia represents an object's resistance to rotational acceleration, similar to how mass resists linear acceleration.
Example 1: Spinning Top
A spinning top has a moment of inertia of 0.001 kg·m² and spins at 100 rad/s. Calculate its angular momentum.
L = I × ω = 0.001 × 100 = 0.1 kg·m²/s
👉 Angular momentum = 0.1 kg·m²/s
Example 2: Bicycle Wheel
A bicycle wheel with moment of inertia 0.15 kg·m² has angular momentum of 3 kg·m²/s. Find its angular velocity.
ω = L / I = 3 / 0.15 = 20 rad/s
👉 Angular velocity = 20 rad/s
Example 3: Solid Sphere
Calculate the moment of inertia of a solid sphere with mass 2 kg and radius 0.5 m about its diameter.
I = (2/5)MR² = (2/5) × 2 × (0.5)² = (2/5) × 2 × 0.25 = (2/5) × 0.5 = 0.2 kg·m²
👉 Moment of inertia = 0.2 kg·m²
Q1. What's the difference between angular momentum and linear momentum?
Angular momentum describes rotational motion, while linear momentum describes straight-line motion. Angular momentum depends on the distribution of mass relative to the axis of rotation.
Q2. Why is angular momentum conserved?
Angular momentum is conserved when no external torque acts on the system, similar to how linear momentum is conserved when no external force acts.
Q3. Can angular momentum be negative?
Yes, the sign of angular momentum indicates the direction of rotation (clockwise or counterclockwise).
Q4. How does moment of inertia affect angular momentum?
Higher moment of inertia means more resistance to rotation, so for the same angular velocity, the angular momentum will be larger.
Q5. What's the relationship between torque and angular momentum?
Torque is the rate of change of angular momentum, just as force is the rate of change of linear momentum.
For further understanding and validation of the formulas used above, we recommend exploring these authoritative resources: