Can you me with Newtons 3rd Law

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Discussion Overview

The discussion revolves around understanding Newton's 3rd Law in the context of a pulley system involving two masses. Participants are exploring how to find tension forces, acceleration, and magnitudes in scenarios where boxes push against each other through pulleys.

Discussion Character

  • Homework-related
  • Technical explanation

Main Points Raised

  • One participant expresses confusion about finding tension force and acceleration in pulley systems, indicating a lack of clarity regarding Newton's 3rd Law.
  • Another participant requests a specific example to avoid repeating the definition of the 3rd Law, suggesting that context is important for understanding.
  • A third participant presents a specific example involving two masses (4kg and 3kg) in a frictionless pulley system and mentions relevant equations like fnet=ma and fg=mg.
  • A later reply suggests starting with a net unbalanced force of 10N to calculate acceleration and describes how to find tension for both masses, emphasizing that the tension values should be consistent.

Areas of Agreement / Disagreement

The discussion does not appear to reach a consensus, as participants are at different levels of understanding and are presenting various approaches to the problem without resolving the initial confusion.

Contextual Notes

Participants have not fully defined all variables or assumptions, and there is a reliance on specific examples that may not cover all scenarios involving Newton's 3rd Law.

slobodan48
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how do you find the Tension force,acceleration,magnitude.
Its those questions where you have pullys,boxes pushing each other...
I am really confused for the 3rd law
 
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slobodan48 said:
how do you find the Tension force,acceleration,magnitude.
Its those questions where you have pullys,boxes pushing each other...
I am really confused for the 3rd law

Do you have a specific example? I'd hate to just vapidly repeat the definition of the 3rd law, which you can easily find anywhere and everywhere...
 
Two masses are places in a frictionless pulley system.Solve for the acceleration and tension forces.
1st box is 4kg and the other is 3kg

well i know,
fnet=ma
fg=mg
ff=muFn
 
You could start by saying that there is a net, unbalanced force of 10N (For GCSE level thought - or you can do 9.81m/s/s, if you like), pulling one up and one down.
This is accelerating both the masses (7kg total), use your formula to find the acceleration.
The tension will be ml times (g + this acceleration) for the light mass and also mh times (g- this acceleration) for the heavy mass. Those two values should be the same, natch - as a check.
etc etc - you can put in the numbers
 

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