That devastating moment when you thought you were hot stuff for mastering kinematics and basic mechanics only to get absolutely demolished by partial differential equations in college.
High school physics: "Calculate where the ball lands." College physics: "Derive the wave function for a quantum particle in a three-dimensional potential well with time-dependent boundary conditions."
The mathematical glow-up between high school and university physics is like going from "I can ride a bike" to "Now design and build a fusion reactor." No wonder so many physics majors have existential crises by sophomore year!