If two or more masses are connected by spring elements, the basic principles remain the same.
We have:
If we move all terms to the left side of the equal sign except for the external force , we have:
We have to make some assumptions about the relative motions of each mass.
- For example, we assumed that the , which results in part (b) of the diagram.
- If we instead assumed that , we would have part (c), where the directions of the forces associated with are the opposite. However, this assumption still generates the same equations of motion.