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