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