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JEE Main 2005 (AIEEE) · Friction on an Incline

Friction on an Incline question from JEE Main 2005 (AIEEE)

Q30JEE Main 2005 · AIEEEMedium

Friction on an Incline

A smooth block is released at rest on a 45∘45^\circ incline and then slides a distance ′d′'d'. The time taken to slide is ′n′'n' times as much to slide on rough incline than on a smooth incline. The coefficient of friction is

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Answer: (b)

  1. The block is sliding, so the friction is kinetic.
  2. At 45∘45^\circ: trts=11−μk=n⇒μk=1−1n2\dfrac{t_r}{t_s} = \dfrac{1}{\sqrt{1-\mu_k}} = n \Rightarrow \mu_k = 1 - \dfrac{1}{n^2}
  3. So the answer is (b) μk=1−1n2\mu_k = 1 - \dfrac{1}{n^2}.
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