Look who's rolling slowly

Hefei Science Museum Innovation Exhibits Deepening Design and Production Service Project Exhibition 1- See Who Rolls Slowly

Exhibition dimensions: approximately 3.0 x 1.2 x 1.5 meters (width x depth x height)

Knowledge points:

A wheel with the same appearance and mass but uneven mass distribution rolls down on the same track at the same time, with significant differences in rolling speed. Some wheels even come to a standstill on inclined tracks. Through this phenomenon of counter experience and counter intuition, it inspires the audience to explore the differences in the rotational inertia of cylinders with uneven mass distribution and think about the scientific principles behind them.

Participation method: Mechanical interaction

Display items include a simple balance, three transparent hollow wheels, and a set of three inclined rails of the same specifications. The outer dimensions and total mass of the wheel are the same, with a transparent outer shell and a hollow interior. It contains particles of three different densities. The audience can weigh three wheels on a scale with the same weight. Place the three wheels in the starting slots of the three inclined rails, press the release device, and the three wheels will start rolling down along the inclined rails. It can be observed that although the three wheels have the same shape and weight, there is a significant difference in the rolling speed. You can also weigh on the balance and observe whether the three wheels have the same mass.

Design and process requirements:

2.0mm thick cold-rolled steel plate is used to make sheet metal frames, and the surface is treated with metal paint.

Track: Three sets of tracks with the same height, inclination, and length, ensuring that wheels with uneven mass distribution roll off on the same track. The starting point at the upper end of the inclined track is equipped with a limit device and a simultaneous release device to ensure that the three wheels can depart simultaneously when the audience interacts. Acrylic sheet is carved and processed using a CNC engraving machine, and the surface is flame polished to ensure the overall transparency of the track. 304 stainless steel bars are precision machined using CNC machines to produce each transmission structural component and release mechanism.

Wheel: The external dimensions of the wheel are the same, and the total mass is also the same. The outer shell of the wheel is transparent and the interior is hollow. It contains three different types of particles. Wheel A is filled with lighter particles, Wheel B is filled with particles with a density of about 2/3, and Wheel C is filled with particles with a density of about 1/3 higher. There are scale markings on one side of the wheel, allowing the audience to observe how many particles are inside. The transparent acrylic wheel is precision machined using a CNC lathe and then flame polished on the surface. It is bonded with acrylic special adhesive to ensure that there are no bubbles on the bonding surface and the overall transparency of the interactive parts is guaranteed;

Balance: Two trays with a pointer in the middle, easy to operate, responsive, stable and durable.

Other requirements:

Make the following props separately for conducting supporting educational activities:

A set of two transparent hollow wheels with the same appearance, but each containing liquid and particles;

A set of two solid wheels with the same appearance but different masses;

A set of two identical transparent hollow wheels with a filling port design;

A timer.