General Science: Physics, Chemistry and Biology Basics
The General Science part asks elementary physics, chemistry and biology of the kind taught at school: units, matter, the human body and health.
Physics
- Speed = distance / time; average speed uses total distance over total time.
- Force is measured in newtons, work and energy in joules, power in watts.
- Newton's laws: inertia; F = ma; every action has an equal and opposite reaction.
- Matter exists as solid, liquid and gas; heat travels by conduction, convection and radiation.
Chemistry
- Atom, element, compound and mixture are different things; water is H2O, carbon dioxide is CO2.
- Acids turn blue litmus red; bases turn red litmus blue; pH 7 is neutral.
- A physical change alters state only; a chemical change produces a new substance.
Biology
- The human heart has four chambers; blood groups are A, B, AB and O.
- Photosynthesis: carbon dioxide + water gives glucose + oxygen, in sunlight, inside chloroplasts.
- Deficiency diseases: vitamin A and night blindness, C and scurvy, D and rickets, B1 and beriberi.
Worked example
A vehicle covers 150 km in 2 hours 30 minutes. Convert the time first: 2.5 hours. Speed = 150 / 2.5 = 60 km/h. The usual error is dividing by 2.3 or by 2, which gives a wrong figure; the unit conversion must come before the division.
Traps
- Mixing mass (kg) with weight (newtons).
- Confusing plant and animal cells: only plants have a cell wall and chloroplasts.
- Matching a deficiency disease to the wrong vitamin.