Timeline for Work kinetic energy theorem
Current License: CC BY-SA 4.0
11 events
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| Mar 31, 2019 at 17:33 | comment | added | nasu | . Now, if you want to replace the work of some internal forces by changes in PE then is your choice and is a quit common treatment. But by no means does it imply that the work-energy does not work or that there is no consensus. Maybe some high school textbooks authors are confused and spread the confusion to their students. The work-energy theorem after all can be derived directly from Newton's second law so it works every time when Newton's second works. This means ANY system treated under the classical mechanics assumptions. | |
| Mar 31, 2019 at 17:27 | comment | added | nasu | For a system of particles, the work-energy theorem states that the change in the KE is equal to the net work done by both external and internal forces. This is the standard formulation for a system of particles. | |
| Mar 31, 2019 at 14:39 | comment | added | Farcher | @nasu The extract from Moran’s book makes me feel that there is no consensus on what the work-energy theorem is and that being the case why it is necessary to define it? | |
| Mar 31, 2019 at 14:30 | comment | added | nasu | The work-energy theorem does not relate to potential energy, just work and KE. There is no need to introduce PE in order to apply the work-energy theorem. If the internal friction in the spring is strong enough that the spring remain at rest after compression then you should take in consideration these forces too. The work of the NET force is equal to the change in KE. Again, there are no cases when the theorem does not work. There are cases when it is not applied correctly. | |
| Mar 31, 2019 at 14:26 | comment | added | nasu | You cannot compress a spring without moving the parts of the spring and even the center of mass of the spring. If you compress an ideal spring for a while and then remove the compressing force the spring will oscillate so it does have kinetic energy. | |
| Mar 31, 2019 at 14:13 | comment | added | nasu | The term "Work-energy" theorem refers to the connection between work and KINETIC energy. There is no separate theorem called "work-energy" theorem and having a different meaning. courses.lumenlearning.com/boundless-physics/chapter/… | |
| Mar 31, 2019 at 14:08 | comment | added | Farcher | @Nasu please note that I have differentiated between the work - kinetic energy theorem and the work - energy theorem. The second works for all situations the first does not. I did this because of the title of this question. | |
| Mar 31, 2019 at 14:04 | comment | added | nasu | 1. A key point which is omitted is that the change in kinetic energy equals the NET work. 2. The W-E theorem works for individual particles as well for systems of particles. Most mechanics books treat the case of systems of particles a little bit after the case of point particles. 3. There are no cases when the W-E does not work. It works very well for the compression of a spring or any other process. You just have to apply it properly. | |
| Mar 31, 2019 at 13:51 | comment | added | nasu | Even after editing, the question promotes misleading or even wrong statements. | |
| Mar 31, 2019 at 11:33 | history | edited | BioPhysicist | CC BY-SA 4.0 |
Changed some confusing wording given the subject of the answer
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| Mar 31, 2019 at 10:42 | history | answered | Farcher | CC BY-SA 4.0 |