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