State space system model derivation - hard and really need help fast - PLEASE!!! Hi, Just found this site (a little too late I fear!). I have an assignment due tomorrow and I can not solve the last part of it. We are able to source information from anywhere to complete the assignment and you guys are my last hope!!! I have a system model digram which I have saved as an image and placed here: (It's just too big to add as an attachment) http://www.megaupload.com/?d=03HUNNYJ [Broken] (Close the popup and wait for the timer to count down then you can download the picture) I have to represent this system in terms of the state space variables outlined on the sheet. I can create state equations for the current and the motor's angular velocity but I cant get the third state space equation. ie. derivitve of Tension = ????? I have worked out the the derivitive of the Tension = K(vw-vs) but dont know if that is correct or where to go from there. This is a fairly hard problem and I dont know if this is the right section to place it but I am hoping someone could help me???!!! Thanks Jamesponty Ps. Im not sure which forum to put this in for the best results so im double posting it. Sorry to do this but I need a result quickly!!