Physics
Physics in UPCATET is numerical and concept-testing: units and dimensions, kinematics, laws of motion, work–energy, gravitation, properties of matter, heat, waves and sound, optics, electrostatics, current electricity, magnetism and modern physics.
Core rules
- Equations of motion hold only for uniform acceleration; v² = u² + 2as is the fastest route when time is not asked.
- Newton's second law is vectorial: resolve along and perpendicular to an incline, with friction opposing relative motion.
- Conservation of energy, momentum and charge short-circuits long calculations.
- Sign convention for lenses and mirrors: distances measured against the incident light are negative.
- Ohm's law with series/parallel rules; P = V²/R explains why a bulb dims when another is added in series.
Worked example
A ball is thrown vertically upward at 20 m/s (g = 10 m/s²). Time to the top: v = u − gt → 0 = 20 − 10t → t = 2 s. Maximum height: v² = u² − 2gh → 0 = 400 − 20h → h = 20 m. Since the motion is symmetric and air resistance is ignored, the total flight time is 4 s and the ball returns at 20 m/s downward. The standard error is quoting 2 s as the total time.
Traps
Mixing cm and m mid-calculation; omitting the square root in RMS speed; using g = 10 when the paper implies 9.8; adding a scalar to a vector; mis-signing image distances in mirrors; applying the parallel formula to resistors in series; reading velocity off a distance–time graph as if it were speed.