A flexible elastic object to store mechanical energy. It has a unique name and the following parameters:

• rest length: is the length of the spring as it is not compressed or stretched.
• length: is the initial spring length
• stiffness: is the level of spring resistance to compression or stretching
• damping: is level of spring ability to disperse stored energy, an internal viscosity
• body 1 and 2: are the bodies to which the spring is fixed
• local position 1 and 2: are the local positions of the spring ends relative to its center in the non-deformed state
• position 1 and 2: are the global positions of the spring ends
• force: is the force that acts along the spring