science high school ngss ps2-1 physics chemistry periodic elements motion 8th grade force vector acceleration torque scalar velocity rotational newton math common core exponents projectile displacement distance kinematics mass si units hs-ps1-1 angular lever 8.ee.4 5.nbt.2 5th grade symbols circular motion speed trajectory centripetal gravity adding gravitation sliding subtracting orbit block resultant symbol position element measurements base unit laws rotational motion quantity types rate mathematics two dimension hs-ps1-2 prefix friction 8.ee.7