PART 2 Energy Skate Park - The Law of Conservation of Energy
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Last updated 23 days ago
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One observation that appears everywhere in the universe is that energy cannot be created or destroyed. This is called the “Law of Conservation of Energy.” Energy cannot be created or destroyed; it can only change forms. It is also called "The First Law of Thermodynamics."
If energy isn’t created or destroyed, that means all of the energy the skater gained from its height should be transferred to its speed at the bottom, and all of its speed at the bottom should be transferred to its height on the other side.
But when friction is present, some kinetic energy is turned into thermal energy (heat) instead, and now there is less usable energy available to turn into height on the other side.
However, the energy doesn't disappear when it is "lost." The wheels, rail, and surrounding air all heat up slightly. You can feel the same thing right now: rub your hands together quickly. You can feel the thermal energy that is given off as a result of friction.
Unfortunately, even though the thermal energy was not "lost," it isn't useful anymore. You burned calories to rub your hands together, but the heat from your hands is now in the environment. You can't "gather it up" and use it again to power your body. You'll have to eat instead, and that food energy has to come from another source, too.
This is referred to as The Second Law of Thermodynamics: All energy is eventually dissipated (spread out) as unusable heat. This disordered, unusable energy is referred to entropy, and as the 2nd law describes, entropy
is always increasing in the universe.
This is why the skateboarder couldn't go as high as time went by; instead of all of the kinetic energy becoming height (gravitational potential energy), some of it was turned into thermal energy (heat) instead.
To sum all of this up, another way to think about the Law of Conservation of Energy is that you can't get out what you don't put in.
But a word to the wise: As the 2nd Law of Thermodynamics states, all energy eventually becomes dissipated over time. Therefore, you actually have to put more work in than you hope to get out. Essentially, you must shoot for the stars if you want to reach the moon.
Sounds like there's a life lesson in there somewhere...
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