物體外形與滾速的關係 (The relationship between the shape and the rolling speed of an object)
You need to prepare a table, two books which are the same weight, a big plastic ring, two bottle caps which are also the same size, a small ball, plastic band and a partner.
What we do is to put those books under the edge of the table and make the table tilt. Then stick the caps together and make a dish. Tell your partner to hold the dish, and you take the small ball and plastic ring, then put at the highest point on the inclined surface of the table mutually. And then let them roll.
Then you will see the ball rolls the fastest, the second is the dish, and the last one is the plastic ring.
Why?
The rolling speed and the mass of surroundings have relationships. The distribution of a mass is closer to the fulcrum, the inertia of revolution will become smaller, it also means it turns more easily so that the rolling speed will become faster. In this experiment, the distribution of each masses is not the same. For example, the plastic ring in the middle of the table, it is the farthest, its inertia of revolution is the biggest, but the rolling speed is the smallest. The mass of the ball is the nearest so that its inertia of revolution is the smallest but the rolling speed will be the biggest.