Imagine that there are three cans, each can has its own components.
The first is an empty can, the second is a can filled with solid, and the third is a can filled with liquid.
Let them roll on a slope simultaneously. Which one is the fastest or which is the slowest?
In this simulation, the circle represents the can while the square indicates its content.
If the content is solid, the square goes with the circle. If the content is liquid, the square rotates freely inside the circle.
Simulation renews as you click the screen.