A particle $\left(\mathrm{m}=1\mathrm{}\mathrm{k}\mathrm{g}\right)$ slides down a frictionless track $\left(\mathrm{A}\mathrm{O}\mathrm{C}\right)$ starting from rest at a point $A$ (height $2\mathrm{}\mathrm{m}$ ). After reaching $C,$ the particle continues to move freely in air as a projectile. When it reaching its highest point $\mathrm{P}$ (height $1\mathrm{}\mathrm{m}$ ), the kinetic energy of the particle (in $\mathrm{J}$ ) is: (Figure drawn is schematic and not to scale; take $g=10\mathrm{}\mathrm{m}{\mathrm{s}}^{-2}$ ) ______________.