In the study of physics,the keyword resistance can be found in many laws and phenomena. The fundamental reason for the ubiquity of resistance is that everything is a contradictory unity composed of positive and negative aspects. The stable state of things is the result of the balance between spear and shield. When the balance is disrupted,the contradiction becomes apparent and the result is that the trend of resisting state changes. Energy,momentum or matter undergoes transfer during the process of resistance. Understanding this universal principle not only makes learning more efficient and enjoyable,but also allows one to appreciate the beauty and profound meaning of physics.