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I read that angular momentum is just pointed perpendicular to the plane of rotation (disk) as a convention.

Force is the change in momentum over time.

Is there actually a force in the direction of the angular momentum when the disk's angular velocity is actually accelerated even further?

When the disk's angular velocity is accelerated (jerk from perspective of linear) further... the disk lifts up to a higher latitude.

So if the disk was at 0 latitude spinning perfectly in balance without any precession.... wouldn't a further acceleration of the disk cause a change in momentum resulting in a force upwards? Because angular momentum is pointing straight up.

If I am wrong.... then the angular momentum does not actually point perpendicular in the real world.

I ask... because... unless it is an illusion... I have seen rotating disks actually lift up but only when the angular velocity is being accelerated at a high rpm. I have not ruled out some kind of aerodynamic effect.

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  • $\begingroup$ But you can convert angular momentum into a force by accelerating the angular momentum (applying more constant force to the rotor, increase angular velocity). So my question is... where does that force go if you happen to accelerate the angular momentum when the top is already spinning perfectly upright? The top has reached some kind of artificial limit? At that time, the top has 0 torque from gravity. $\endgroup$
    – nate sire
    Sep 2 at 18:25
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Is there actually a force in the direction of the angular momentum when the disk's angular velocity is actually accelerated even further?

No. Angular momentum ($\mathbf L$) is not a force. But the reality of the $\mathbf L$ vector can be seen when a top is precessing on the ground for example.

A tilted top is under a torque $\tau$ (also a vector, and the derivative of angular momentum with respect to time). If there is no spinning (zero initial $\mathbf L$) the top falls down at an accelerated angular velocity. $\mathbf L$ and $\tau$ have the same direction in this case. $\mathbf L$ grows from zero to a maximum value when it lies on the ground.

If it is spinning when tilted, the effect of the same torque (as a good derivative) is to modify the existing $\mathbf L$. And that means adding an horizontal arrow ($\tau$) to an inclined arrow ($\mathbf L$). The process results is a continuous movement of $\mathbf L$, forming a conic shape. What is seen is a precession of the top.

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