Physics (Physics / Basic Physics)
What the exam tests
Physics and Basic Physics cover mechanics, waves, electromagnetism, thermodynamics, and atomic/nuclear topics. The paper tests setup: choosing a coordinate system, drawing forces, and applying conservation laws before substituting numbers.
Core rules
- Newton's second law: net force equals mass times acceleration; resolve forces along chosen axes.
- Energy: change in kinetic plus potential energy equals work by nonconservative forces; momentum is conserved when external impulse is negligible.
- Waves: speed equals frequency times wavelength; reflection, refraction, and superposition; path difference determines interference.
- Circuits: Ohm's law V=IR; series current is the same, parallel voltage is the same; Kirchhoff's laws handle networks.
- Thermodynamics: first law delta U = Q - W; ideal gas PV=nRT.
Worked example
A ball is thrown horizontally at 20 m/s from a 45 m cliff. Take g=10 m/s^2 and ignore air resistance. Vertical motion: 45 = (1/2)gt^2, so t^2=9 and t=3 s. Horizontal velocity is constant, so range = 20 times 3 = 60 m. The reasoning separates vertical and horizontal motion; the vertical drop sets the time, and that time sets the horizontal distance.
Traps
Mixing up the sign of g; using speed instead of velocity; forgetting that tension and normal force are constraints; applying energy conservation when friction does work; misreading a v-t graph, whose area is displacement; and reporting too many significant figures. In circuits, a common error is treating parallel resistors as series.