Pulley System Part c: Homework Statement & Relevant Equation

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SUMMARY

The discussion focuses on understanding the mechanics of a pulley system, specifically addressing the confusion surrounding the motion of a balanced system. Participants clarify that a balanced system can still exhibit movement due to the net force being zero, which allows for the acceleration of components within the system. The calculation for average kinetic energy is discussed, with emphasis on the relationship between the movement of the weight and the cable length. It is established that when the weight descends by one unit, the cable must move through the pulley, resulting in the weight moving only half as far as the cable length.

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Seneka
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Homework Statement


upload_2018-10-23_13-51-33.png

upload_2018-10-23_13-51-47.png


2. Relevant equation

The Attempt at a Solution

...[/B]
Part c)
I'm confused as to how the actual pulley system works. If its balanced wouldn't it be stationary. How does it move?
I thought that since its balanced the acceleration of the system is constant and therefore to find the average kinetic energy of the system, I would just do 1/2 x (2000 + 1000) x (9/30)^2
The answers say that the weight only moves half as far. How do you know this?
 

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Seneka said:
If its balanced wouldn't it be stationary. How does it move?
I believe by "balanced" they mean that the net force is zero.

Seneka said:
The answers say that the weight only moves half as far. How do you know this?
Note how the cable attaches to the weight. When the weight moves down by 1 unit, how much cable must move through the pulley above the car? (You might want to play around with a piece of string to better visualize what happens.)
 
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