What Forces Act on a Pulley System with Two Masses?

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SUMMARY

The discussion centers on the forces acting on a pulley system with two masses, specifically analyzing the tension (T) in the string and the gravitational force (Mg) acting on each mass. The right mass experiences a vertical force of Mg - Tcosϑ, while the left mass experiences Mg - T. The analysis concludes that the left mass moves upwards while the right mass moves downwards and horizontally, with the initial vertical acceleration of the right mass being negative. The participants utilize equations of motion, including T - mg = m(dV_v/dt) and centripetal acceleration terms, to derive the relationship between the two masses' movements.

PREREQUISITES
  • Understanding of Newton's laws of motion
  • Familiarity with tension in strings and pulley systems
  • Knowledge of centripetal acceleration and its application
  • Ability to analyze forces in two dimensions
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  • Study the derivation of forces in pulley systems using free body diagrams
  • Learn about the implications of tension in non-stretchable strings
  • Explore the effects of initial velocities on the motion of connected masses
  • Investigate the role of angular motion in pulley systems and its equations
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Physics students, mechanical engineers, and anyone interested in understanding dynamics in pulley systems and the forces acting on connected masses.

  • #61
Your original approach was good. You noted that the downward force on m2 is greater than the downward force on m1 (except initially when θ = 0 and the forces are equal). Equivalently, you could say that the upward force on m2 is less than the upward force on m1. So, the upward acceleration of m2 is less than the upward acceleration of m1. Thus m1 rises more quickly.
 
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  • #62
TSny said:
Your original approach was good. You noted that the downward force on m2 is greater than the downward force on m1 (except initially when θ = 0 and the forces are equal). Equivalently, you could say that the upward force on m2 is less than the upward force on m1. So, the upward acceleration of m2 is less than the upward acceleration of m1. Thus m1 rises more quickly.

What about this reasoning ?

After a very short time , right mass would be moving horizontally towards right .This would lead to lengthening of right string .Correspondingly left string shortens and in the process left mass moves upwards .Left mass would be higher than right mass .
 
  • #63
TSny said:
Yes, I enjoyed this one a lot.

Now , I can also say , ME TOO :biggrin:
 
  • #64
Jahnavi said:
What about this reasoning ?

After a very short time , right mass would be moving horizontally towards right .This would lead to lengthening of right string .Correspondingly left string shortens and in the process left mass moves upwards .Left mass would be higher than right mass .
After a very short but finite time, the right mass would be moving both to the right and upward.
At t = 0, the right mass is only moving to the right. But at this instant the string on the right is not getting longer (##\dot r_2 = 0##). Neither mass is moving upward at t = 0. So, the argument is a little vague. But the argument is suggestive of what's going on.
 
  • #65
Jahnavi said:
Now , I can also say , ME TOO :biggrin:
That is very good to hear:smile:
 
  • #66
I learned a lot from you TSny . Excellent discussion !

Thanks a lot !

A big Thank You @Chestermiller :smile:
 

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