Spin Dynamics Made Visible with the Rotational Inertia Demonstrator

Teaching rotational dynamics, angular acceleration, and moment of inertia often feels abstract—equations on the board without something real for students to grasp. The Rotational Inertia Demonstrator gives you a clear, repeatable setup where students change mass distribution, pulley radius, and torque to watch how angular acceleration responds.

Arbor Scientific’s Rotational Inertia Demonstrator (P3-3545) combines a variable-radius pulley and moveable masses to show—in seconds—how torque (τ) and moment of inertia (I) determine angular acceleration (α). It’s a classroom-ready tool that turns rotation from formula to visible motion.

Torque & Angular Acceleration: Change the pulley radius and apply the same force; students observe angular acceleration change in line with τ = Iα.

Moment of Inertia & Mass Distribution: Slide masses outward/inward to change I while keeping torque constant—students watch acceleration slow or increase.

Calculate vs. Measure I: Use the theory of mass distribution (rods + masses) and compare to measured acceleration data to compute I—then discuss sources of error.

• Visual and hands-on: Students physically see how moving masses and changing radius affect rotational motion—no more only using textbook diagrams.
  
  

• Repeatable classroom demo: Robust construction and precise controls make it reliable and teacher-friendly.
  
  

• Supports modeling & inquiry: Great for guided labs, whiteboard discussions, student predictions, and matching experimental to theoretical results.
  
  

• Ideal for advanced courses: Works for AP Physics C, college intro mechanics, or honors classes—so your investment scales across years