Physical Sciences
Core Concepts
Understand matter (atoms, elements, compounds, mixtures), states of matter and phase changes (melting, boiling, sublimation), and conservation of mass in chemical reactions. Know Newton's laws: inertia (objects resist changes in motion), F = ma, and action–reaction pairs. Distinguish speed (scalar) from velocity (vector with direction) and know that acceleration is a change in velocity. Understand energy forms (kinetic, potential, thermal, chemical) and conservation of energy. Know basic electricity (current, voltage, resistance; Ohm's law V = IR) and wave properties (wavelength, frequency, amplitude).
Traps
Questions often confuse mass with weight, speed with velocity, and heat with temperature. Watch for phase-change questions where temperature stays constant during melting or boiling. Another trap is assuming energy is "used up"; it is transformed. Also be careful with action–reaction pairs: they act on different objects and do not cancel.
Rule of Thumb
For motion problems, identify knowns (distance, time, force, mass) and the unknown, then choose the equation that links them: speed = distance/time; F = ma; V = IR.
Worked Example
A 2 kg cart accelerates at 3 m/s². Using F = ma, F = 2 × 3 = 6 N. If the applied force doubles to 12 N, acceleration doubles to 6 m/s² (mass constant). This illustrates a direct proportional relationship between force and acceleration.