A `10 kg` block is initially at rest on a rough horizontal surface. A horizontal force of `60 N` is required to set the block in motion . After it is in motion , a horizontal force of `50 N` is required to keep the block moving with constant velocity . The ratio coefficient of static and kinetic friction is

Options

A. `(1)/(2)`
B. `(2)/(3)`
C. `(6)/(5)`
D. `(3)/(2)`

Answer

C

Explanation

`60 = mu_(s) mg` (i)
`50 = mu_(k) mg` (ii)
`(mu_(s))/(mu_(k)) = (60)/(30) = (6)/(5)`

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