Inertia balance rvfm ph10587 p an apparatus for investigating the nature of mass and the distinction between mass and weight the device allows the measurement of inertial mass as opposed to gravitational mass for a regular balance p p the principle of operation is to record the oscillations produced when the tray is deflected then released the frequency of vibration will depend on the unknown mass in the tray being higher for a lower mass and lower for a higher mass the object to be