5 ms·
Fundamentally, yes. All motion does end up adding entropy to the environment. This is especially egregious for fossil fuels which are literally combusted/oxidiz
by ainoobler 2y ago
Fundamentally, yes. All motion does end up adding entropy to the environment. This is especially egregious for fossil fuels which are literally combusted/oxidized to move chunks of metal on wheels carrying different kinds of cargo. Electric vehicles change the dynamics somewhat but the motion of magnets still ends up contributing entropy to the environment at a somewhat reduced rate than fossil fuel vehicles.
- tsimionescu 2y agoHeat and entropy are different concepts. Also, motion can reduce entropy locally, even if globally it always increases. For example, when a puddle freezes, the puddle's entropy goes way down. The entire Earth's entropy can also go down, as long as the entropy of the universe increases.
- ainoobler 2y agoHow are heat and entropy different?
- tsimionescu 2y agoHeat is energy that causes something to raise in temperature, and is measured in Joules. Entropy is a harder to pin down concept, related to the internal state of a system, and is measured in Joules/kelvin. In certain processes, the change in entropy is equal to the change in heat divided by the temperature of the system.
- ainoobler 2y agoSounds like it's the same thing.
- tsimionescu 2y agoIt is not. Two bodies can have different entropy even if they are emitting the same amount of heat.
- ainoobler 2y agoWhere are the calculations?
- tsimionescu 2y agodS = dQ / T
- ainoobler 2y agoSo T = dQ/dS. Seems like the same thing.
- tsimionescu 2y agoIf they were the same thing, then T=1. Since there are many many bodies with T != 1, it follows that dQ is rarely equal to dS.
- HPsquared 2y agoThey are closely related but not the same. DeltaS = DeltaQ /T A lot of it comes down to whether a process is reversible or not. I've taken multiple courses on thermodynamics and still only understand it a little.