Laboratory equipment, namely, force tables for use in laboratories to determine the vector sum of the different forces; torque tables for use in analyzing problems of torque and center of gravity; equilibrium cranes for use in illustrating that static equilibrium is achieved when both the forces and the moments are in equilibrium; mass hangers for hanging laboratory weights; air track substitutions, consisting of a perforated triangular "rail" emitting air for use in studying frictionless lin...