I have a question from a student that I am having difficulty answering properly.
We are discussing a pully with a string going over it and the string not slipping
against the pulley with two different masses attached to each end of the string,
one on each side of the pulley.
I drew the free body diagram of the pulley showing a supporting force at the
center and a Tension downward on the left and also one downward on the right of
the pulley.
The student's comment was "aren't all parts of the string that are in contact with
the pulley also supplying a torque on the pulley?" In other words, he is not
comfortable with the notion of just the two tensions supplying torque but feels
there are other torques that need to be included in the net torque acting on the
pulley.
What might be a good response to this concern?
Thanks for the help, David Abineri dabineri@choice.net