241
Physics ;-;
(lemmy.nz)
you are viewing a single comment's thread
view the rest of the comments
view the rest of the comments
this post was submitted on 29 Sep 2026
241 points (97.6% liked)
Memes
17170 readers
1813 users here now
Post memes here.
A meme is an idea, behavior, or style that spreads by means of imitation from person to person within a culture and often carries symbolic meaning representing a particular phenomenon or theme.
An Internet meme or meme, is a cultural item that is spread via the Internet, often through social media platforms. The name is by the concept of memes proposed by Richard Dawkins in 1972. Internet memes can take various forms, such as images, videos, GIFs, and various other viral sensations.
- Wait at least 2 months before reposting
- No explicitly political content (about political figures, political events, elections and so on), !politicalmemes@lemmy.ca can be better place for that
- Use NSFW marking accordingly
Laittakaa meemejä tänne.
- Odota ainakin 2 kuukautta ennen meemin postaamista uudelleen
- Ei selkeän poliittista sisältöä (poliitikoista, poliittisista tapahtumista, vaaleista jne) parempi paikka esim. !politicalmemes@lemmy.ca
- Merkitse K18-sisältö tarpeen mukaan
founded 4 years ago
MODERATORS
okay so i took my ebike out the other week. did the same route at two different speeds. first time at 10mph, second at 20mph.
i had a quarter charge left at the end of the 10mph ride. according to all the maths i have ever mathed, the 20mph ride should have consumed more battery. so how the fuck did i end up with half a charge left after the faster ride
i blame ignoring air resistance on all my physics forever.
Could have to do with efficiency at various motor speeds. With IC engines, they don't take constant fuel input and don't produce constant power or force over the rates at which they support spinning.
I understand electric motors have full access to their peak torque at any speed but I am not sure if that also means equal efficiency for the full rpm curve, so that could be a part of it.
Also I wonder about wheel efficiency and how that curve would look. Like if your tires are a bit under pressure, I could see more deformation being possible at lower speeds, which could mean the tires themselves become stiffer and more efficient as they spin faster.
And finally, 10 and 20 mph are both pretty low speeds as far as air resistance is concerned. Air resistance is more significant in how it scales. I forget the exact formula but I do remember that air resistance has a term with a higher exponent than the formula for work done (which boils down to distance travelled), which absolutely means that the force required to overcome air resistance increases much faster than the formula for the result of applying that force, but exponents can take a while go really get going.
Oh actually one more thing, when running a device like that, there will be some portion of energy it requires for just being on and another required for gaining and maintaining speed. It could be that the constant power requirements are significant compared to the amount of power required to get to and hold either 10 or 20 mph. Could even be a short or malfunction of some sort. If that's the case, then the fact that your 20 mph trip only took about half the time could have saved more power than the extra needed to move twice as fast.
So my guess is the amount of extra air resistance going from 10 to 20 mph was less than some set of benefits you gained from that same speed increase, of which I listed the ones I could think of above.
nooooo don't tell me that i've been fighting a short for three months. i thought i had it fixed finally
I'll never drive slower than 150mph from now on.
Rookie numbers, I never drive slover than 242km/h.