a device for use in the control of mechanical forces is provided . the device includes first and second terminals for connection to components in a system for controlling mechanical forces and independently moveable . the device further comprises a hydraulic device connected between the terminals and containing a liquid . the hydraulic device is configured to produce upon relative movement of the terminals , a liquid flow to generate an inertial force due to the mass of the liquid to control the mechanical forces at the terminals such that they are substantially proportional to the relative acceleration between the terminals .