Angular Momentum: Axis of Rotation & Centre of Mass

In summary, when using the equation L=(moment of inertia)*(omega) to calculate the angular momentum of a rigid body rotating around a moving axis, the axis of rotation must pass through the centre of mass of this body and be a symmetrical axis. For a fixed and non-moving axis, it is not necessary for the axis to pass through the centre of mass. However, in the case of a "free spinning" object, it has a "natural" axis which can be calculated using the same equation. More information on angular momentum can be found on Wikipedia.
  • #1
glen_ky
4
0
1) When we use the equation of L=(moment of inertia)*(omega) to calculate the angular momentum of a rigid body rotating around a moving axis, why the axis of rotation must pass through the centre of mass of this body and the axis should also be a symmetrical axis?

2) If for a fixed and non-moving axis, is this necessary to pass through the centre of mass?

Pls help, thanks.:eek:
 
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  • #2
If someone could help...pls...Thanks...:frown:
 
  • #3
Why nobody can help~~~how dissapointed...haizzzZzzzz...
 
  • #4
Moving axis? How is the axis moving?

You can calcultate an angular momentum about any real fixed (relative to object) axis, but it the object is "free spinning", then it has a "natural" axis.

Maybe wiki will help here:

http://en.wikipedia.org/wiki/Angular_momentum
 

Related to Angular Momentum: Axis of Rotation & Centre of Mass

1. What is angular momentum?

Angular momentum is a measure of the rotational motion of an object around an axis. It is a vector quantity that takes into account both the speed and direction of rotation.

2. What is the axis of rotation?

The axis of rotation is an imaginary line that an object rotates around. It can be any line passing through the object's center of mass or a fixed point.

3. How is angular momentum related to the axis of rotation?

The direction of the angular momentum vector is perpendicular to the plane of rotation and points along the axis of rotation. This means that the axis of rotation is always parallel to the direction of the angular momentum vector.

4. What is the center of mass?

The center of mass is the point at which an object's mass is evenly distributed in all directions. In other words, it is the average position of all the mass in an object.

5. How does the center of mass affect angular momentum?

The center of mass plays a crucial role in determining the angular momentum of an object. The closer the axis of rotation is to the center of mass, the smaller the object's moment of inertia and the greater its angular momentum will be.

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