Timeline for What's the difference between friction and viscous force according to a perspective from molecular level?
Current License: CC BY-SA 3.0
10 events
| when toggle format | what | by | license | comment | |
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| Jul 4, 2017 at 19:05 | comment | added | Steeven | @Hisab. No (actually, only if the load is extremely large, such as when milling metal). Under most normal circumstances kinetic friction can be calculated with $f_k=\mu_k n$ with $\mu_k$ being constant. Surface area is not included here. | |
| Jul 4, 2017 at 17:09 | comment | added | Kawsar Ahmed | So, does kinetic friction depend on surface area? | |
| Jul 4, 2017 at 17:00 | comment | added | Steeven | @Hisab Uh, that is indeed a good question. When i say friction here, I mean kinetic friction. The thing is that a sliding box feels kinetic friction, while a rolling ball feels static friction. And they behave differently. In your case, when comparing to drag forces, only kinetic friction makes sense. | |
| S Jul 4, 2017 at 15:48 | history | edited | JMac | CC BY-SA 3.0 |
Fixed spelling.
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| Jul 4, 2017 at 15:43 | comment | added | JMac | @Hisab In that scenario there are several things that can happen. First and foremost; when determining friction there is some "coefficient of friction" (for the type of friction that "doesn't depend on contact area"). The thing is, this coefficient is experimentally determined; and will vary if you go between extremes like a cube with high surface area to a sphere with low surface area. Another big difference is that the sphere might not slide. A sphere is able to roll, and therefore the point of contact has no relative movement. This means the resistance comes from inertia. | |
| Jul 4, 2017 at 15:39 | comment | added | Kawsar Ahmed | So, why is it easier to make a sphere run on a surface than a cube of same mass? The sphere gets less friction than the cube although both have same mass, getting same normal force from the surface. Please, help me here. | |
| Jul 4, 2017 at 15:29 | comment | added | Steeven | At not too high loads (normal forces) (or in other words, not too big micro deformations, which means most everyday cases), friction does not depend on surface area / contact area | |
| Jul 4, 2017 at 15:24 | answer | added | user154997 | timeline score: 2 | |
| Jul 4, 2017 at 15:19 | review | Suggested edits | |||
| S Jul 4, 2017 at 15:48 | |||||
| Jul 4, 2017 at 15:01 | history | asked | Kawsar Ahmed | CC BY-SA 3.0 |