Key idea
Conservation of energy
Start with the central idea, then test it against a concrete element or example. A scientific model is useful when we know what it explains — and where its limits are.
Conservation of energy
The key idea
Energy can move between stores and cross a system boundary, but for an isolated system total energy is conserved.
Why it matters
Thinking in terms of energy often lets us solve a problem without following every detail of the motion.
A picture to remember
Key idea
Conservation of energy
Guided example
Conservation of energy
Start with the central idea, then test it against a concrete element or example. A scientific model is useful when we know what it explains — and where its limits are.
Put it into practice
Conservation of energy
Choose a concrete case linked to Conservation of energy. Write down the known information, what you are trying to find, and the units. Then state the rule, model or trend you will use. If a calculation is involved, keep the units visible at every line; if it is conceptual, state what changes and what remains fixed.
Check your answer
A strong answer contains four things: the starting situation, the variable that changes, the direction or numerical result, and one check. The check can be a unit, an order of magnitude, a limiting case or a comparison with a familiar example.