A block of mass m slides along a floor while a force of magnitude F is applied to it at an angle $\theta$ as shown in figure. The coefficient of kinetic friction is $\mu$k. then, the block's acceleration 'a' is given by :
(g is acceleration due to gravity)
${F \over m}\cos \theta + {\mu _K}\left( {g - {F \over m}\sin \theta } \right)$
${F \over m}\cos \theta - {\mu _K}\left( {g - {F \over m}\sin \theta } \right)$
$-$${F \over m}\cos \theta - {\mu _K}\left( {g - {F \over m}\sin \theta } \right)$
${F \over m}\cos \theta - {\mu _K}\left( {g + {F \over m}\sin \theta } \right)$
