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Ask iit jee aieee pet cbse icse state board community Community Discussion Question: Find friction
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[Post New]6 Apr 2008 19:53:36 IST
    Subject: Find friction
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srini (305)

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Hey,
A disc starts rotating with a constant angular acceleration 1rad/sec2 about a fixed vertical  axis perpendicular to its plane through its centre.A coin of mas 10g is placed on the disc at a distance of 10cm from the axis.The coeffecient of friction between the disc and the coin is .2.The value of the frictional force on the coin a t=1s will be  what?
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[Post New]6 Apr 2008 20:09:58 IST
    Subject: Re:Find friction
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karthik2007 (3349)

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Hi!

Simple question.

angular velocity of the disc at t=1s = @t = 1x1 = 1rad/s.

Now, if the coin is to stay on the disc, centripetal force is to be provided by frictional force, hence:

f(t=1s) = .01 x 1 x .1 = .001N
Will nip in at times to solve problems :)
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[Post New]6 Apr 2008 20:15:41 IST
    Subject: Re:Find friction
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ramyani (2390)

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 0.01
it is not important where u stand, but in which direction u are moving
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[Post New]6 Apr 2008 20:16:29 IST
    Subject: Find friction
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karthik2007 (3349)

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Note that the coefficient of friction given is superfluous data.
Will nip in at times to solve problems :)
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