Oscillating Meter Stick

DCS Code: 1K20.43 Last Updated: March 27, 2026
Log in to reserve this demo

Purpose

Demonstrates that friction is proportional to normal force. As a meter stick's center of gravity shifts between two rotating rollers, the normal force distribution changes, causing the dominant friction force to reverse direction. The result is self-sustaining oscillatory motion driven entirely by friction.

Two large tan cylindrical rollers mounted on black metal bearings on a wooden base, with a meter stick resting across them. A hand positions the stick. A pulley and belt are visible on the right side.
Figure 1: Parallel roller apparatus with meter stick. The belt and pulley (right side) drive both rollers in the same direction, causing the meter stick to oscillate back and forth.
Demo Apparatus