When forces $F_1, F_2, F_3 $ are acting on a particle of mass m such that $F_2$ and $F_3$ are mutually perpendicular, then the particle remains stationary. If the force $F_1$ is now removed than the acceleration of the particle is
Here $ F_1 = F_2 +F_3 $ $ \therefore a = { F_1 \over a } $

