General Science
General Science covers school-level physics, chemistry and biology, with applied health and environment questions.
Physics
- SI units: metre, kilogram, second, ampere, kelvin, mole, candela.
- Newton's laws; F = ma; work = force x displacement; power = work/time.
- Ohm's law V = IR; series and parallel resistance; electrical safety.
Chemistry
- Atomic number = protons; mass number = protons + neutrons.
- Acids have pH below 7, bases above 7; neutralisation; common salts and uses.
- Air composition, water hardness, carbon compounds and fuels.
Biology
- Cell organelles; plant versus animal cell; photosynthesis.
- Human systems: digestive, circulatory, respiratory and nervous.
- Blood groups; vitamins and deficiency diseases; communicable versus non-communicable diseases.
Worked example
A 10 kg body is pushed so that it accelerates at 2 m/s². Find the force. F = ma = 10 x 2 = 20 N. Mass is in kilograms and acceleration in m/s², so the answer is in newtons. Weight would instead be mg, about 98 N, because g is about 9.8 m/s².
Traps
- Mass versus weight; weight = mg.
- Speed versus velocity, which has direction.
- Atomic number versus mass number.
- Reading pH as acidity when the scale is inverse.
- Confusing a deficiency disease with its vitamin.