The tension force of a pulley

May 2017
Sri Lanka
I have a problem that, If there is no friction in the pulley why the T1 force equals to the T2 force. Can you give me the reasons for that.


Apr 2017
The only possible explanation for the diagram can be that the system is not static ...

one weight is accelerating up , the other down.
Last edited:


PHF Helper
Jun 2010
Morristown, NJ USA
If you pull on a rope you introduce a tension into that rope, which is constant throughout its length. The only way that the tension can vary along the length of a rope is if there is an additional force introduced somewhere between the ends - for example if there were additional weights hanging on the rope or if the pulley was not frictionless. If the tension varied otherwise, from one segment of rope to another, then from F=ma the rope would have to accelerate, and since the mass of the rope is assumed to be zero it would accelerate at an infinite rate.