Vibrations induced by a periodic displacement of the point of support of the spring. In this experiment a connecting rod, driven by an eccentric, imparts a such that on revolution of the eccentric is equal to one revolution of the phase recorder. In this experiment the exciter unit is driven from a gearbox via a flexible coupling such that one revolution of the contra rotating discs is equal to one revolution of the phase recorder. Vibrations induced by applying a periodic disturbing force to the mass. 

Technical specifications:-

•  Two methods of exciting forced vibration are adopted; either by oscillating the upper spring mounting with SHM at variable frequency or by applying a rotating out balance force at variable frequency to the vibrating mass.

•  Simple adjustments can be made to the apparatus and the motion of the mass can be readily observed and recorded on the two pen recorders provided. 

•  The use of so called “Black Boxes” has been avoided, a feature welcomed by most teachers.

•  Adopting the well tried features of the simple Vibration Apparatus, the mass carriage is constrained by rollers on vertical guide ways to provide minimum uncontrolled damping. 

•  Two pen recorders are provided, a continuous paper recorder for amplitude and frequency measurements and a rotating drum recorder for amplitude and phase measurements.

•  Variable viscous damping is provided by an oil dashpot.

•  Experiment manual.

Dimensions and weight

•   880 x 580 x 1240 mm.

•   Net Weight : 75 kg.