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Why Does Angular Momentum Point Perpendicular to the Rotation?

Why Does Angular Momentum Point Perpendicular to the Rotation?

by Raul Barrea | Oct 15, 2026 | article, Rotation & Gravitation

Foundational Physics Short Answer: For a wheel spinning about its fixed symmetry axis, angular momentum points along the axle, perpendicular to the wheel’s plane. It describes the wheel’s overall sense of rotation, not the direction in which a point on the rim...
Why Is Angular Momentum Conserved?

Why Is Angular Momentum Conserved?

by Raul Barrea | Oct 15, 2026 | article, Rotation & Gravitation

Foundational Physics Short Answer: Angular momentum stays constant when the net external torque on a system is zero. Forces within the system can change how its parts rotate, but they exchange angular momentum rather than create or destroy the total. A torque from...
Why Does Pulling Your Arms In Make You Spin Faster?

Why Does Pulling Your Arms In Make You Spin Faster?

by Raul Barrea | Oct 15, 2026 | article, Rotation & Gravitation

Foundational Physics Short Answer: Pulling your arms toward your body moves mass closer to the axis of rotation, reducing your moment of inertia. If outside twisting forces are negligible, angular momentum stays constant, so you spin faster. Your muscles also do work...
Why Does Moment of Inertia Depend on the Axis of Rotation?

Why Does Moment of Inertia Depend on the Axis of Rotation?

by Raul Barrea | Oct 15, 2026 | article, Rotation & Gravitation

Foundational Physics Short Answer: Moment of inertia depends on the axis of rotation because different axes put an object’s mass at different distances from the axis. Mass farther from the axis contributes more strongly to rotational inertia. The same rod is...
Why Does Torque Depend on Perpendicular Distance?

Why Does Torque Depend on Perpendicular Distance?

by Raul Barrea | Oct 15, 2026 | article, Rotation & Gravitation

Foundational Physics Short Answer: Torque depends on perpendicular distance because only the part of a force that acts to turn an object about a pivot produces torque. The turning effect is determined by the shortest distance from the pivot to the force’s line of...
Why Can Momentum Be Conserved in One Direction but Not Another?

Why Can Momentum Be Conserved in One Direction but Not Another?

by Raul Barrea | Oct 15, 2026 | article, Energy & Momentum

Foundational Physics Short Answer: Momentum is conserved separately in each direction only when the net external impulse in that direction is zero. During a brief collision, an external force can change the horizontal momentum of an object without appreciably changing...
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