ST156 · Equilibrium in a Single Plane

Experimental apparatus for the static equilibrium of a planar body with a fixed and a floating support

A model ladder resting between a fixed bottom support and a floating upper support, loaded by a sliding clamp weight at a position the student chooses, provides a physical illustration of the principle of freeing — the mental operation that converts supports into reaction forces on the free-body diagram. Cables with calibrated weights in the horizontal and vertical directions let the student replace the real support reactions with cable tensions and watch the ladder remain in equilibrium — a direct experimental confirmation of the two equilibrium conditions ΣF = 0 and ΣM = 0.

Experiments

Experimental development of the principle of "freeing" in statics
Calculation of the support reactions from the position of the clamp weight and the inclination angle
Application of the 1st and 2nd equilibrium conditions
Full compensation of the support reactions by cable forces in the horizontal and vertical directions
Distinction between fixed and floating bearings
Influence of the clamp-weight position on the support reactions
Influence of the inclination angle on the support reactions

Ladder model

Length 650 mm

Self-weight 2 N

Built-in rule graduation 1 mm

Supports

Configuration 1 fixed bearing + 1 floating bearing, both clamped to the mounting frame

Guide pulleys 3 — redirect the cable weights into the

x

and

y

directions

Loading

Sliding clamp weight 20 N, positioned with built-in rule

Cable weights 3 × 1 N hangers · 12 × 1 N · 9 × 5 N

Measurement

Position built-in rule (1 mm); tape measure 3000 mm (1 mm)

Delivery

Ladder model with built-in rule
2 bearings (1 fixed, 1 floating)
3 guide pulleys, 3 cables, sliding clamp weight
Calibrated weight set, tape measure
Storage case with foam inlay, instruction manual

28 kg

Part of package

Fundamentals of Structural Mechanics

A complete set of experimental modules covering the core topics in strength of materials — elastic line, torsion, Euler buckling, frame deformation, plastic bending, and static equilibrium.

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