Work Energy Theorem of a spring

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Homework Help Overview

The discussion revolves around the Work Energy Theorem as it applies to a spring system, specifically examining the relationship between potential and kinetic energy in a scenario involving a disk on a slope.

Discussion Character

  • Exploratory, Assumption checking, Problem interpretation

Approaches and Questions Raised

  • Participants are questioning the correctness of the potential energy change calculation and its implications on kinetic energy. There are concerns about the relevance of certain parameters, such as the initial speed of the disk and the meaning of "kg = 0.5m." Some participants are exploring the implications of the disk's kinetic energy in relation to its motion down the slope.

Discussion Status

Several participants have expressed doubts about the consistency of the information provided in the problem. There is an ongoing examination of the assumptions made regarding the disk's motion and energy transformations, with some guidance offered on interpreting the radius of gyration.

Contextual Notes

Participants note potential inconsistencies in the problem statement, particularly regarding the disk's ability to complete two revolutions based on its kinetic energy. There is a suggestion that some information may be extraneous or misleading.

theBEAST
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Homework Statement


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The Attempt at a Solution


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Is this correct? Is the change in potential energy Ufinal-Uinitial?

My answer turns out to be a positive number, so intuitively does this mean that some of the kinetic energy went into potential and thus the final potential energy is greater than the initial?
 
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Looks fine, but several things bother me.
What is "kg = 0.5m"?
Why are you told the initial speed of the disk?
Seems to me that the disk does not have enough KE to travel two revolutions down the slope, and it won't recoil that far either. But I cannot think of another interpretation of the question.
 
haruspex said:
Looks fine, but several things bother me.
What is "kg = 0.5m"?
Why are you told the initial speed of the disk?
Seems to me that the disk does not have enough KE to travel two revolutions down the slope, and it won't recoil that far either. But I cannot think of another interpretation of the question.

kg is the radius of gyration, it would be used to solve for the total KE which is the sum of the rotational and translational motion. This is given to throw the students off I think :P
 
theBEAST said:
kg is the radius of gyration, it would be used to solve for the total KE which is the sum of the rotational and translational motion. This is given to throw the students off I think :P
OK, but that doesn't satisfy my last point. As far as I can see, the information given is inconsistent. It would not travel two whole revolutions, in either direction. (Would somebody check that?) Superfluous information is one thing, contradictory information quite another.
 

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