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Physics For Engineers2D

Rotational Motion - Theory & Concepts - Angular Momentum

A comprehensive overview of Rotational Motion explaining angular kinematics, dynamics, energy, and momentum.

Open the complete lesson
Interactive engineering simulation

Angular Momentum Skater Simulator

Pull the rotating masses inward or outward. When friction and external torque are neglected, moment of inertia decreases, causing spin velocity to increase.

Initial Arm Radius (ri)
1.30 m
m
0.402.00

Drag for exploration or enter an exact value. Press Enter to apply; Escape restores the current value.

Current Arm Radius (rc)
0.70 m
m
0.302.00

Drag for exploration or enter an exact value. Press Enter to apply; Escape restores the current value.

Core Skater Inertia (I_body)
2.0 kg·m²
kg·m²
0.56.0

Drag for exploration or enter an exact value. Press Enter to apply; Escape restores the current value.

Initial Angular Speed (ωi)
2.5 rad/s
rad/s
0.56.0

Drag for exploration or enter an exact value. Press Enter to apply; Escape restores the current value.

Governing Laws
Moment of Inertia
I=Ibody+2mr2I = I_{body} + 2m \cdot r^2
Conservation of Momentum
L=Iiωi=IfωfL = I_i \cdot \omega_i = I_f \cdot \omega_f
Rotating skater demonstrating the conservation of angular momentumOrbit expands as spin speed (ω) increases
Angular Momentum (L)
17.68 kg·m²/s
Current Angular Speed (ω)
5.09 rad/s
Model scope and verification

Use the displayed units and idealizations, then verify the governing balance or compatibility equation before interpreting the result.