Timeline for For a solid sphere rolling (pure roll) up a slope (with friction) does friction play a role in slowing it down?
Current License: CC BY-SA 4.0
6 events
| when toggle format | what | by | license | comment | |
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| Dec 5, 2018 at 13:20 | comment | added | Gert | shouldn't the friction be acting so as to maintain it in pure roll, and so then shouldn't friction do work? A common misconception. The friction force does not do any work because it doesn't move wrt the surface. If you hold your finger against a surface against friction but w/o moving the finger, is work performed? No because no displacement! | |
| Dec 5, 2018 at 13:18 | vote | accept | karun mathews | ||
| Dec 5, 2018 at 13:16 | comment | added | karun mathews | Thanks a lot! Another doubt, I think that friction is the only force present - that can produce torque in the sphere, as all the other forces act through the center of mass of the sphere. So if the sphere slows down $while $$in $$pure $$roll$ shouldn't the friction be acting so as to maintain it in pure roll, and so then wouldn't friction do work? | |
| Dec 5, 2018 at 12:26 | comment | added | Gert | Correct. Only if the friction is insufficient to maintain $v=\omega R$ would the friction force do work, because it 'slides' over the surface. $-mg\Delta h$ is the only work done here. | |
| Dec 5, 2018 at 12:07 | comment | added | karun mathews | So, friction doesn't do any work on the sphere, while the sphere is rolling up? If I use the work - energy theorem: Work done= ΔKinetic Energy. Will the work done term only have -mgΔh ? | |
| Dec 5, 2018 at 11:51 | history | answered | Gert | CC BY-SA 4.0 |