Physics Tutorial: Combination Circuits - Physics Classroom Newton's Laws. Balanced vs. Unbalanced Forces; Change of State; Fnet = m•a; Force and Motion; Mass and Weight; Match That Free-Body Diagram; Net Force (and Acceleration) Ranking Tasks; Newton's Second Law; Normal Force Card Sort; Recognizing Forces; Air Resistance and Skydiving; Solve It! with Newton's Second Law; Which One Doesn't Belong ...