The coefficient of static friction between a wooden block of mass 0...

$F . B . D .$ of the block is shown in the diagram

Since block is at rest therefore

$fr - mg = 0 . . . \left(1\right)</p><p>$F - N = 0 . . . \left(2\right)$</p><p>$fr \le \muN$</p><p>In limiting case</p><p>$fr = \muN = \muF \ldots \left(3\right)

Using eq. \left(1\right)$and \left(3\right)</p><p>$∴ \muF = mg$</p><p>$⇒ F = $\dfrac{0 . 5 \times 10}{0 . 2} =$25N$</p></blockquote>$