First of all, we should know that as long as the volume ratio and the mass ratio are the same, obviously, by calculating the volume ratio of two cylinders, the mass ratio of two cylinders can be obtained.

The radius of the first root is twice that of the second root, so according to the area formula of the circle (s=πr? It can be seen that the bottom area is 4 times that of the second root, the height of the second root is 2 times that of the first root, and the first root is 1/2 times that of the second root.

According to the cylindrical volume formula (V=πr? H), we can know that the volume of the first root is twice that of the second root (4* 1/2=2), so the volume of the second root is half that of the first root, and its weight is also half that of the first root, that is, 20 kg.