Why does the heaviest point on a spinning ball tend to become the topmost pole?

Question

I have a mostly hollow, small clear plastic ball. Inside the ball is a weight stuck to the edge but the weight is smaller than the ball so the ball will always come to rest with the weight at the bottom when placed on a smooth surface.

I've been spinning it on my desk with the weight at the top, it spins well despite it being top heavy, I assume like a gyroscope. If I spin it with the weight at the bottom however, it loses stability and it very quickly slows down until it regains stability with the weight at the top again, with further experimentation I found that wherever the weight is, once the ball starts spinning it stabilises with the weight at the top.

What causes the rotational energy to transform into gravitational potential energy?

Any why is the ball more stable with the weight at the top axis than with it at the bottom axis?

Answer 1

Veritasium has made a video about this. With this as a solution video. Someone also posted this video response, which also has a good explaination.

Even though they use a disk with a unbalanced center of mass, the same still applies to your ball. The rotating ball will try to rotate around its center of mass. However if this does not align with the point of contact with the floor then the point of contact will be dragged along in a circle. If there is friction between the floor and the ball then this will cause the rotating ball to precess.

The reason why this "pushes" the center of mass to the top is better explained in the videos. Although it still seems counter intuitive to me, we have to remember that our intuition is not always right.