In the track shown in figure -3.94 section AB is a quadant of a circle of 1 metre radius in vertical plane. A block is released at A and slides without friction until it reaches at B. After B it moves on a rough horizontal floor and comes to rest at D, 3 metres from B the coefficient of friction between floor and the body will be :

Options

A. `1//3`
B. `2//3`
C. `1//4`
D. `3//8`

Answer

A

Explanation

` KB =mg(1)`
` (1)/(2)mv^(2)=Mg `
`v^(2) =20`
` v^(2) =20`
`v= sqrt(20)m//s`
By conservation of energy ,
`(1)/(2)mv^(2)-mu mgx =0`
`(1)/(2)(20) -mu (10)(3)=0`
`mu =(1)/(3)`