The toy "tumbler" will automatically stand up after being pulled. What is the secret of tumbler's failure?

Objects that are light on the top and heavy on the bottom are relatively stable, that is, the lower the center of gravity, the more stable it is. When the tumbler is in equilibrium in an upright state, the distance between the center of gravity and the contact point is the smallest, that is, the center of gravity is the lowest. After deviating from the equilibrium position, the center of gravity always rises. So the balance of this state is a stable balance. Therefore, no matter how the tumbler swings, it will not fall. Another example is the experiment of "rolling on a cone" that we saw in the Science and Technology Museum. Because of the shape of the cone and the shape of the tracks on both sides, its center of gravity is falling, but it seems to be rising, which does not conform to the facts in life. But this is just an illusion. Seeing its essence clearly, the center of gravity is lowered, so the lower the center of gravity, the more stable it is. In order to increase the stability of objects in life, we often increase the weight below, such as fan base, microphone bracket, bus stop sign and so on.

Using this feature, we can do many interesting experiments and explain some phenomena. If you can become a beetle, open a capsule and put a small ball in it, you can turn your head back and forth. We often put a box on the table a little, but it won't fall. This is because the box is close to one end of the table, which is the "center of gravity", so the box hangs but will not fall. Acrobats who walk a tightrope also hold the balance bar to lower their center of gravity and achieve balance.

Self-made method of tumbler: choose the packing box of spherical plastic Chinese medicine pills, which can be opened from the middle, just two hemispheres. Put a proper amount of plasticine or wet plasticine in one hemisphere to become the bottom of the tumbler, and stick a conical hat outside the other hemisphere to become the top of the tumbler. After the two hemispheres are buckled, draw a face and it is ready.