science high school ngss ps2-1 physics chemistry periodic elements motion 8th grade force vector acceleration torque common core scalar velocity rotational newton math 8.ee.4 5.nbt.2 5th grade exponents projectile displacement distance kinematics si units mass hs-ps1-1 angular lever rate mathematics types hs-ps1-2 two dimension 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