ACCORDING TO HCV AND OTHER BOOKS IT IS TOLD TO CALCULATE TORQUE ABT THE COM

IS IT NECESSARY

WELL I THINK THE ANS IS NO

not necessarily, usually the torque is calculated about the COM  but it can also be calculated about any point that is not accelerating.for accelerating points you have to consider the torque of the pseudo forces. 

TO CALCULATE TORQUE ABT THE COM has an advantage,

In that case torque due to mg ( wt )  don't contribute.

But torque can be calculated abt any point.

I m not sure hcv told to calculate torque abt ony COM. In fact there r many solved and unsolved examples in hcv where torque was calculated abt a point which is not COM.

For example, hcv , vol I , pg 185, solved example 8----torque was calculated abt a point which is not COM.

YEAH TORQUE CAN BE CALCULATED ABOUT ANY POINT.....CONSIDER TORQUE DUE TO PSEUDO FORCES IF THAT PT. IS ACCELERATED.....COM  IS  PREFFERED  COZ  PSEUDO  FORCES  PASS  THROUGH COM,   TORQUE  IS   ZERO.....SO  ONE  DOSEN'T  NEED  TO  THINK  ABOUT  PSEUDO  FORCES  DUE  TO  ACCELERATION  AT  ALL....!

congratulations for 1000 posts @ Varun

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see the concept of torque is that any point we consider the the torqu should be balanced .

so obviously if for one point the torque is balanced the torque shoud be zero for any other poin in that FRAME and not only in the body