GED and HiSET science — energy in systems

Energy links almost every part of the GED and HiSET science tests: the same idea that explains a power plant also explains a light bulb, a warehouse hoist, a leaf and a human cell. Energy and related systems is one of the themes the GED science test is organized around, and HiSET science questions regularly draw on it in both physical and life science. This material follows energy through the systems adults deal with every day, from the electric bill to the food on the table.

The quiz traces the chain of conversions in a natural-gas power plant (chemical to thermal to mechanical to electrical) and in a hydroelectric dam (gravitational potential energy of stored water turning turbines). It computes the efficiency of real devices — an LED bulb against an old incandescent one — and explains where the rest of the energy goes: not destroyed, but mostly turned into waste heat, which is why energy is still conserved. It classifies renewable and nonrenewable sources and states a real trade-off of solar power fairly. It calculates work as force times distance for a worker pushing a cart, power as work divided by time for two hoists, and the cost of running a space heater from its kilowatt rating, the hours of use and a price per kilowatt-hour. It closes the loop in living systems: photosynthesis stores the Sun's light as chemical energy, coal and other fossil fuels hold energy captured by plants long ago, cellular respiration releases the chemical energy in food, and a solar panel turns light directly into electricity.

The flashcards review the law of conservation of energy, the formulas for efficiency, work, power and electrical energy, and the main conversions and source types.

The written work asks you to explain energy chains and trade-offs in your own words and to set out calculations with units: the energy and cost of an appliance, the efficiency of a device and where its losses go, or the path of energy from the Sun to a light switch. In the oral exam an examiner presents energy situations one at a time, asks you to name each conversion and to reason through the numbers, and closes with brief feedback.

Prices in the questions are examples, written in words (cents and dollars). This is independent practice material based on the publicly described content of the two tests; it is not produced or endorsed by GED Testing Service or by ETS.

• Trace energy conversions in fossil-fuel, hydroelectric and solar systems
• Calculate efficiency and explain where wasted energy goes under conservation of energy
• Classify energy sources as renewable or nonrenewable and state trade-offs fairly
• Compute work, power and electrical energy in kilowatt-hours, and the cost of electricity
• Connect photosynthesis, fossil fuels and cellular respiration as stages in the flow of energy

Practice material written by Zestly, based on the published descriptions of the GED Science test (ged.com; energy and related systems) and the HiSET Science subtest (hiset.org: physical science and life science content).