Beam supported at ends with platform scales and toy truck as load to demonstrate moment arms.

What it shows:

The concept of moment arms is exemplified by this model of a truck on a bridge.

How it works...

Magnetic blackboard mechanics with spring balances and weights.

What it shows:

Solve a problem in composition of concurrent forces by graphical or trigonometric means.

How it works:

The blackboard mechanics set¹ includes apparatus to demonstrate most of the common laws of statics and some dynamics. The pieces of apparatus are held on the blackboard by magnets and, although not large, are fairly visible in the lecture hall. A booklet with a few dozen suggested demonstration experiments is included in the set.
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Small ladder against wall with variable load and inclination.

What it shows: 

A small ladder is leaned against a vertical wall. A weight can be moved up succeeding steps to find when the ladder will slip and fall down. The forces holding the ladder in equilibrium are in consideration here.

How it works: 

A short (4 foot) step-ladder leans against the wall. The reaction of the wall may be considered horizontal, tangential friction being negligible (the edge of the ladder is covered with a sheet of...