1. When we lose weight due to eating right and/or exercising (excluding water weight), it's because the air that we breathe out is slightly heavier than the air that we breathe in.
2. When we're burning wood in a fireplace, the heat it gives off is essentially the sunlight that the tree has collected over its lifetime -- i.e. the heat difference between full sun and the shade of the tree.
3. A solar cell producing peak power is slightly colder than one that is either open- or short-circuited.
I should have qualified that by saying it's true to roughly the same degree as the claim that a tree's mass comes from the air. I.e. if you wave your hands and ignore a lot of potentially-important second-order effects, it more or less holds water :).
1. When we lose weight due to eating right and/or exercising (excluding water weight), it's because the air that we breathe out is slightly heavier than the air that we breathe in.
2. When we're burning wood in a fireplace, the heat it gives off is essentially the sunlight that the tree has collected over its lifetime -- i.e. the heat difference between full sun and the shade of the tree.
3. A solar cell producing peak power is slightly colder than one that is either open- or short-circuited.