Physics
Syllabus weight
Measurement and units, kinematics, Newton's laws and momentum, work-energy-power, gravitation, pressure and flotation, heat and temperature, waves and sound, light and optics, electricity and magnetism, and a little modern physics.
Concepts to lock down
Scalars have magnitude only; vectors have magnitude and direction. Distinguish mass from weight (weight = mg), density from relative density, and heat from temperature. Learn Newton's three laws, remembering that action and reaction act on different bodies and therefore never cancel. Memorise the equations of motion: v = u + at, s = ut + at squared over two, and v squared = u squared + 2as. For circuits, use Ohm's law, series versus parallel resistance, and power = voltage times current.
Traps
Prefix conversions (1 km = 1000 m, 1 mm = 0.001 m), confusing frequency with wavelength, believing sound travels faster than light, and assuming zero velocity means zero acceleration: a ball at the top of its flight has v = 0 but a = g.
Worked example
Convert 72 km/h to m/s: 72 multiplied by 5/18 gives 20 m/s. A car at 20 m/s braking at 4 m/s squared stops in t = v/a = 5 s and covers s = v squared over 2a = 400/8 = 50 m. Rule of thumb: convert every quantity to SI units before substituting into a formula.