At a particular moment, a particle experiences a net force of $=(5\mathrm{.}1$N$)+(5\mathrm{.}1$N$).$ At the same moment, its position is $=(2\mathrm{.}1$m$)+(5\mathrm{.}9$m$)+(2\mathrm{.}1$m$)$ and its velocity is $=(3\mathrm{.}9$m$/$s$)+(1\mathrm{.}1$m$/$s$)+(1\mathrm{.}1$m$/$s$).$ The mass of the particle is $0\mathrm{.}21$kg$.$