Something about applied dynamics.

[aiklone1314]

http://img211.imageshack.us/img211/6048/a1a1.gif
http://img17.imageshack.us/img17/6684/b1b1.gif

May i know actually why initially 2SA+SB=l , but after differentiate, it becomes 2 aA = -aB ?
why does the l disappear?

[CFDFEAGURU]

This thread does not belong here. Please move it to the homework thread.

Matt

[tiny-tim]

Hi aiklone1314! :smile:
May i know actually why initially 2SA+SB=l , but after differentiate, it becomes 2 aA = -aB ?
why does the l disappear?

2SA+SB = l, so 2aA+aB=0 (because l is a constant), so 2aA = -aB :wink:

[aiklone1314]

but how to know SA and SB is not a constant?

[tiny-tim]

but how to know SA and SB is not a constant?

If sA is constant, then vA and aA will be 0 (same for sB)

[aiklone1314]

If sA is constant, then vA and aA will be 0 (same for sB)

ok thank you very much...