Or      $\mathrm{Kt}=\mu \mathrm{mg}$

Or      $\mathrm{t}=\mu \mathrm{mg} / \mathrm{K}$

For $\mathrm{t}>\mu \mathrm{mg} / \mathrm{K}:$

net acceleration of block is,

$\mathrm{a}=\frac{\mathrm{F}-\mu \mathrm{mg}}{\mathrm{m}}=\frac{\mathrm{Kt}}{\mathrm{m}}-\mu \mathrm{g}$

which is a straight line with positive slope and negative intercept.

So, for $t \leq \mu m g / K,$ acceleration of the particle is zero

and for $\mathrm{t}>\mu \mathrm{mg} / \mathrm{K},$ acceleration is $\mathrm{a}=| \mathrm{Kt} / \mathrm{m}-$

$\mu g$