The Bridge Problem

DCS Code: 1J40.41 Last Updated: April 6, 2026
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Purpose

A meter stick supported by two spring scales models a bridge: sliding a hanging mass along the stick shows how load position determines the force at each support. Demonstrates torque balance and static equilibrium quantitatively.

Red-and-yellow meter stick supported horizontally by two large Ohaus 20N dial spring scales on vertical rods, with a brass mass hanging off-center from the stick. An Ohaus mass set sits on the green table below.
Figure 1: A red-and-y meter stick supported by two 20 N spring scales. Moving the hanging mass along the stick changes the readings on each scale, demonstrating torque balance.
Demo Apparatus