Three forces $F_{1}=10 \mathrm{~N}, F_{2}=8 \mathrm{~N}, \mathrm{~F}_{3}=6 \mathrm{~N}$ are acting on a particle of mass $5 \mathrm{~kg}$. The forces $\mathrm{F}_{2}$ and $\mathrm{F}_{3}$ are applied perpendicularly so that particle remains at rest. If the force $F_{1}$ is removed, then the acceleration of the particle is: