The shape and characteristics of children's tops

The shape and characteristics of children's tops are round in the upper part and sharp in the lower part. In the past, they were mostly made of wood, but now they are mostly made of plastic or iron. When playing, you can wrap it with a rope and pull the rope hard to make it rotate upright. Or use the elasticity of the spring to rotate. Traditional ancient tops are roughly inverted conical shapes made of wood or iron, and are played by splitting them with a whip.

When the gyroscope rotates, it not only rotates around its own axis, but also makes conical motion around a vertical axis. In other words, the top "rotates" around its own axis and "precesses" around the vertical axis.

That is to say, the top does not stand vertically on the ground, but has a certain deviation from the normal line of the ground and is slightly tilted toward the ground. Therefore, the torque of gravity on the gyro is not zero, and the precession angular momentum of the gyro can balance the effect of the gravitational moment, so the gyro will not fall to the ground when it rotates.