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TIL to keep track of units
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this post was submitted on 07 Sep 2024
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I didn’t do the math, but a person’s got to do more lifting in those 34 years than a car traveling 30 miles at 60 mph carrying 4000 lbs, right?
Without a doubt! Humans and life in general is uber efficient in terms of energy use. Most of the energy of a car is not directly spent for the work. Work is done when moving mass from a lower to a higher place and accelerating it to a higher speed. But once you have accelerated the mass to the cruise speed, it actually does not require any energy to maintain. Rather, the energy is spent by the car to heat up the air, move it around, wear the road and the tires, and make noise.
We use cars because they are muuuch more powerful than humans, at the cost of wasing a lot of energy. Try to push a car uphill, you won't ever succeed without pullies which makes it even slower. Doesn't matter how efficient you are if you cannot output the minimum power required to overcome friction etc.
On the other hand a human on a bicycle is way more effective at moving around than a human on foot. Somehow the bicycle has created a lot of efficiency.
A bicycle allows us to use our strength to go faster, rather than having to move our muscles faster, we can just push harder. It also more directly converts the energy we are consuming into forward momentum than our walking style does. We are pretty efficient at processing the energy out of what we eat and into work done by our muscles, but beyond that, there are certainly locomotion styles that haven't naturally evolved yet that would singnificantly improve how fast we could travel using that energy. Until then, we got smart instead, which really helped.
There are technically types of wheels in nature, but not in animals, the way alot of bacterial flagella operate is basically a wheel. Or more accurately a biological chemical/electric motor, but it spins anyway. And some of them can rotate either direction by engaging a protein cluster that effectively acts as a "reverse gear" like a transmission.
Yes, and gasoline actually has less energy density than body fat at approx. 33 MJ/L vs. 35 MJ/L : https://en.m.wikipedia.org/wiki/Energy_density
The best explanation for the 1000 fold error in your post is explain in top comment from @garfaagel@sh.itjust.works ...