Easily Explain Rotational Inertia

• Two complete discs are included so you can compare the speed as they roll
• You will receive two injection-molded ABS plastic discs, eight solid steel balls, and instructions

The concept of equal mass but different distribution of mass will suddenly have meaning for your students. Instantly change the distribution of mass in these 3 ¹/₂" diameter discs by inserting up to eight solid steel balls into your choice of compartments inside. Replace the top, screw both halves together, and roll the weighted disc down a slope.