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Resolving forces

 
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drgshahbaz1193



Joined: 26 Mar 2010
Posts: 18
PostPosted: Mon May 31, 2010 4:19 pm    Post subject: Resolving forces Reply with quote
WIth the resolving forces problems where we have objects suspended by ropes I have a question about weigth and tension. In the problem where there is a object M and it is sitting on a surface and connected by a rope on a pulley system to a smaller object m that is dandling. In resolving the forces the tension is equal to the weight, so how does the object m fall lower? ALso if the force of the object downward is counteracted by the tension then where does the tension felt near object M come from?

I know this is a really silly question but it has been a while since I took general physics and I am a little confused. Thanks.
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mcat_premed3832



Joined: 19 Oct 2006
Posts: 413
PostPosted: Mon May 31, 2010 7:28 pm    Post subject: Reply with quote
Quote:
In resolving the forces the tension is equal to the weight, so how does the object m fall lower? ALso if the force of the object downward is counteracted by the tension then where does the tension felt near object M come from?


The 2 questions are, of course, related.

Object m falls because object M has no friction.

When you resolve the forces around M, you get the force of tension T to the right (caused by mg) and you get no counteracting force to the left (which would be, normally, friction). If there is no friction, then mass m could be as small as an atom and mass M can be as big as an elephant, as long as the rest of the data is typical first year imaginary estimates (weightless cord and frictionless pulley) then not only does the elephant move to the right, it must accelerate to the rate because of the tiny T.
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