General Science with an environmental emphasis
Core science
General Science tests basic physics, chemistry and biology with an environmental tilt. Learn definitions and units, then apply them to pollution, energy and ecosystems.
Physics and chemistry
- SI units: force in newton, energy in joule, power in watt, pressure in pascal. Weight = mass × g; mass does not change with location.
- Energy forms include kinetic, potential, heat, light, chemical and electrical. In a closed system energy is conserved but may become less useful.
- pH below 7 is acidic, 7 neutral and above 7 basic. CO2, methane, nitrous oxide and water vapour are greenhouse gases; ozone depletion by CFCs is a separate problem.
- Combustion needs fuel, oxygen and ignition; incomplete combustion produces carbon monoxide.
Biology and environment
Photosynthesis uses CO2 and water with light to make glucose and release oxygen; respiration reverses the energy flow. In a food chain, energy transfer is inefficient, roughly 10% at each step, so top predators are few. Decomposers recycle nutrients.
Worked example
A 2 kg object moves at 3 m/s. Kinetic energy = ½mv² = ½ × 2 × 3² = 9 J. The reasoning: square the speed first, multiply by mass, then halve. Using 3 instead of 9 would wrongly give 3 J.
Traps
Confusing mass with weight; treating speed and velocity as identical; saying ozone causes the greenhouse effect; and reversing the photosynthesis equation.