Conservation of Energy: Feynman's Physics Explained
There is a law that, as far as we know, is never broken: energy is conserved. But what is energy? Imagine a child with 28 indestructible blocks. Each day the total is still 28, even when some are hidden in a box or out on the lawn — the mother just needs a clever formula to count the hidden ones. Energy is like that. It is not a 'thing' you can hold; it is a number you compute from a formula, and the astonishing fact is that the total never changes, no matter how the energy shifts from one form to another.
The big idea
Energy changes form but the total amount never changes.
Think about it
When a swinging pendulum slows and stops, where did its energy go? Is it really gone, or just hidden in a form harder to count?
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