Finding the tension in a pulley that rotates

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    Pulley Tension
AI Thread Summary
To find the tensions T_1, T_2, and T_3 in a rotating pulley system where m_2 is greater than m_1, it's essential to apply Newton's second law, considering the net acceleration due to the rotation. When the pulley rotates, m_2 will descend, creating a dynamic situation rather than static equilibrium. The tensions will differ from the static case, as T_1 will equal m_1g minus the force due to acceleration, while T_2 will equal m_2g plus the same force. The net acceleration affects the calculations, requiring a reevaluation of the forces acting on each mass. Understanding these dynamics is crucial for accurately determining the tensions in the system.
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Homework Statement


pulley_zps70f8d0bc.png

m_2>m_1
The pulley rotates.
Find the tensions, T_1, T_2, T_3

Homework Equations


Newton's laws


The Attempt at a Solution


I know how to solve the problem if the pulley doesn't rotate because the systems would be in equilibrium (Newton's first law) and dividing into 3 systems (one for each tension) you get T_1=m_1g, T_2=m_2g and T_3=m_1g+m_2g.

But I have no idea what changes when the pulley starts rotating. Can somebody give me some leads?
 
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Well if the pulley starts rotating it will do so in such a way so that m2 will start falling because it is more massive. The only difference here is that when you do Newtons Second Law on the system, there will be a net acceleration.
 

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