How do you apply Hooke's law to particles joined to multiple springs. For example in the diagram below: 0rigin |-\/\/\/\/- P1 - /\/\/\/\- P2 -/\/\/\/\/\/-| I mean, would you have to introduce a new variable to indicate displacement if you altered one of the springs? Also, suppose the left spring is compressed, does this mean that the middle and right hand springs are extended? So the tension is -ve for spring one and positive for springs two and three? I would appreciate if someone clarified this for me as it would better my understanding. This type of question seems to come up quite frequently.