I think since $F=ma$ thus the frictional force can produce acceleration in a body in some cases, is my view correct?please suggest some example then. If not then where i went wrong?
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You know that friction can reduce the speed of a body, don't you? If the speed changes, you have an acceleration. – nasu Sep 08 '16 at 17:30
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i m not talking about deacceleration i have used the term accelerate.maybe its my fault, i should have mentioned it earlier. – Vidyanshu Mishra Sep 08 '16 at 17:34
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In common language acceleration means an object speeds up, but in physics acceleration is any change (faster or slower) in velocity over time. Yes, friction can produce acceleration of an object-- it can slow it down. – pentane Sep 08 '16 at 17:34
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so i should ask "can friction speed up a body??" – Vidyanshu Mishra Sep 08 '16 at 17:37
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Yes that would make it clear what your question is. You can edit your post/title rather than making a new post. – pentane Sep 08 '16 at 17:39
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Yes it can. $\Sigma F = m a$ means sum of forces = mass * acceleration, in that sum, one typically includes friction. – Dr. Ikjyot Singh Kohli Sep 08 '16 at 17:55
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can you provide an example of situation to make it clear properly?? – Vidyanshu Mishra Sep 08 '16 at 17:56
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does a wheel-based tennis-ball serving machine rely on friction to increase the speed of an object ("positive acceleration")? – Yorik Sep 08 '16 at 18:00
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1Ever drop an object onto a moving conveyor belt? – dmckee --- ex-moderator kitten Sep 08 '16 at 20:10
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i didn't get you "Yorik" – Vidyanshu Mishra Sep 09 '16 at 06:34
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how would friction accelerate it?? "dmckee" – Vidyanshu Mishra Sep 09 '16 at 06:35
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@Qmechanic,Shouldn't it be reopened.Cuz i don't see any answer of my question at the question u have suggested. – Vidyanshu Mishra Oct 15 '16 at 17:37
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The F in F=ma isn't required to be a frictional force, it's just any force.
If we assume a frictional force, then in physics-language yes, it does cause an acceleration, but in the opposite direction to motion. An object travelling from left to right and slowing down is accelerating, but to the left...for example, if the force slowing it down was a rocket then it would slow, stop, then (in everyday-language) accelerate to the left. In physics language it's always accelerating to the left, even when slowing down or stationary.
Frictional forces generally depend on the relative motions of the two objects involved though, so in your specific case when the relative speeds drop to zero the frictional force drops to zero and the acceleration stops, rather than continuing in style of the rocket example.
The Geoff
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"when the relative speeds drop to zero the frictional force drops to zero" what about static friction? – pentane Sep 09 '16 at 21:12
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Static friction would be applicable if you were still applying a force to the object, but we're not in this context. – The Geoff Sep 26 '16 at 15:49