A Simple Demonstration for the Static Ladder Problem

In the teaching of statics, the ladder problem is a standard two-dimensional exercise. If students can understand how to set up this problem, they can solve almost any other two-dimensional problem. Solving this or any other statics problem requires identifying the forces (such that ΣF = 0) and where they act, and determining the length of the moment arm and the angle between the moment arm and the force (such that Στ = 0). In teaching the ladder problem we begin with a simple diagram of the leaning ladder and ask the students to identify the forces on the ladder and where they act. Students will readily identify three forces: the ladder's weight (mg), the normal force of the ground on the ladder, N, and the force of the wall on the ladder, F_wall, as shown in Fig. 1.