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As shown in the figure, a person of mass 'm' remains stuck to the wall of rotating rotor. What  should be the minimum value of angular velocity \omega [coefficient of friction between wall and man is \mu]

 

Option: 1

\sqrt{\frac{\mu g}{R}}


Option: 2

\sqrt{\frac{g}{R}}


Option: 3

\sqrt{\frac{g}{\mu R}}


Option: 4

\sqrt{\mu g R}


Answers (1)

best_answer

 

 

Sticking of Person with the wall of Rotor(Death well) -

F = weight of person (mg)

\mu R=mg

\mu F_{c}=mg

\mu m \omega_{min}^{2}r=mg

\therefore\ \omega_{min}=\sqrt{\frac{g}{\mu r}}

Where F = friction force

Fc = centrifugal force

 \omega _{min} = minimum angular velocity

\mu=coefficient of friction

r = radius of Rotor

 

 From the figure 

 

\\f_r = mg \\\mu N = mg\;\;[f_r = \mu N] \\\mu F_c = mg\;\;[As\;N=F_c]

\mu m \omega_{min}^2R = mg \Rightarrow \omega_{min} = \sqrt{\frac{g}{\mu R}}

 

Posted by

manish

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