For measuring inertial masses and qualitatively understanding the terms, mass and weight. This principle can be used to determine mass under weightless conditions in space flights.
The apparatus consist of two aluminum trays joined together by a pair of spring steel strips attached to their sides. Trays are about 200mm apart. One of the trays (the oscillating tray) is drilled to hold three equal cylindrical masses and the other tray acting as an anchorage is clamped by a C-clamp to a bench. Supplied with three masses and a cord (does not include a C-clamp).