Conservation of energy — Science definition
Defined in 2 courses:
- Energy remains accounted for across a complete system and its transfers. (Science 6: Matter, Energy & Earth Systems)
- Energy is not created or destroyed in a process; it is transferred or transformed. (Life Science: Biology)
Where it is taught
- Energy Transformations, Conservation & Dissipation — Energy, Heat & Thermal Design, Science 6: Matter, Energy & Earth Systems, Grade 6
- Comparing Photosynthesis & Respiration — Matter & Energy in Living Systems, Life Science: Biology, Grade 10
In use
Conservation of energy says the total before equals the total after, and it says nothing at all about how much of the total ends up where you wanted it.
Energy Transformations, Conservation & Dissipation
Questions using conservation of energy
Problem 1
Which statement correctly uses conservation of energy in Energy Transformations, Conservation & Dissipation?
- One illustrative result establishes every real condition and needs no further evidence.
- Energy that is less useful has been destroyed.
- Conservation means every individual object must keep the same energy.
- conservation of energy: Energy remains accounted for across a complete system and its transfers.
Answer and explanation
conservation of energy: Energy remains accounted for across a complete system and its transfers.
Energy remains accounted for across a complete system and its transfers. A gives 24 ÷ 120 = 20% as visible light and 96 J in thermal pathways. B gives 30% as visible light and 84 J in thermal pathways. B has a larger modeled light fraction for this purpose, but brightness at the page, price, lifetime, and actual measurements would also matter. Both conserve the stated input energy.