A block pressed against the vertical wall is in equilibrium. The minimum coefficient of friction is:

Options

A. `0.4`
B. `0.2`
C. `0.5`
D. none of these

Answer

C

Explanation

Here net driving force
`=mg-(mg)/(2)=(mg)/(2)` downward
Hence friction will act upward and its magnitude should be `f=(mg)/(2)` . If the block `'m'` is stationary the friction between `m` and the wall should be static.
`flef_(lim)`
`(mg)/(2)lemu . N implies (mg)/(2)lemu(mg) implies mu=(1)/(2)` .