11constraint equation is basically stating that the length of an inextensible string is constant . you write it by adding all the lengts of the different parts of the string and then differentiate the equation to obtain a relation between the accelerations of the different masses attached to the string. But it can all be better explained with an example. Post some problem involving it.
1subhash is quite correct but its not only about strings..
'constarint' in lexicon means 'restriction'.
wen we do pulley problems we have the constraint that the lenggth of the strings joining one or more masses wont change.. so if one mass goes in one direction then the other must move in such a way so that THE LENGTH OF THE STRING REMAINS CONSTANT.
again wen we do prob where a ladder slides between two walls we keep in mind dat the length of the ladder remains constant..
i hope now its somewat clear..
33http://targetiit.com/iit_jee_forum/posts/constraint_equation_471.html
11Oh! So that's a constraint equation? I knew this stuff before but I didn't know it was called a constraint equation!