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A rod OA rotates about a horizontal axis...

A rod OA rotates about a horizontal axis through O with a constant anti-clockwise velocity `omega=3 rad//s.` As it pases the positions `theta=0^(@)` a small block of mass m is placed on it at a radial distacne r=450 mm If the block is observed to slip at `theta=50^(@)` the coefficient of static friction bewteen the block and the rod is (Given that ,`sin50^(@)=0766,cos 50^(@)=0.64`)

A

`0.2`

B

`0.55`

C

`0.8`

D

1

Text Solution

Verified by Experts

(d) At the time of slipping maxnimum friction acts on the body

in the frame of rod,
`mg sin theta=muN+mr omega^(2)`
Also, " " `N-mg cos theta`
`:. " " mg sin theta=mumgcostheta+mromega^(2)`
`Here, " " r=0.4.5m, theta=50^(@)`
`sin50^(@)=0.766 "and " cos 50^(@)=0.64`
`:.mu=(mgsintheta-mromega^(2))/(mg costheta)=(gsintheta-romega^(22))/(gcostheta)=0.55`
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