Question
Sun December 18, 2011 By:

Why in vertical motion of pulley T=m1g-m2a?

Expert Reply
Mon December 19, 2011
here m1 is going up and m2 is going down with accl  a.so net force on m1 is in upward dir and net force on m2 is in downward dir.
T is the tension in the string.
for m2:the net force is in downward direction ie net accleration a in downward dir ie net force is m2a. . at a time, in m2, two forces are acting, weight in downward dir and tension of the string in upward.so this net force is m2g-T.
 so,   m2g-T=m2a
for m1:similarly:
T-m1g=m1a
if you solve these equation you can get T.
but T =m2g-m2a
or  T=m1g+m1a
this comes from net force concept.
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