## Wednesday, 5 March 2014

### CONSTRAINTS EQUATIONS

1. This comment has been removed by the author.

2. sir why do we take submission T.a=0?

3. Genius technique I have read arihant in that constraint relation is found by comparing lengths it consumes time this is excellent trick have u discivered it on ur own

4. T.s that is work done by tension.
Since the string is inextensible , we can say that the work done by all the parts of tension should be 0.
therfore T.s = 0 , on differentiating w.r.t time
T.v = 0 , again on differentiating w.r.t time
T.a = 0. quick and efficient.

5. Sir why we took a1 & a2 in upward direction.. In example 5 same as in example 2 v2 in downwards...?

1. a1/a2 and v1/v2 can be taken in any direction you wish.....you must only be careful to mark direction of tension(T) correctly and make sure you take product as Ta (if T and a are parallel) or -Ta (if antiparallel) or Ta*cosB (where B is angle between T and a)

6. Is there any exception where this rule does not work

1. It doesnt work when the angle of strings wrt each other changes as the value of tension chnages. This is called principle of virtual work