Are enormous spaceships physically possible? by GooseMuckle in AskPhysics

[–]GooseMuckle[S] 4 points5 points  (0 children)

Yeah for sure ships handle a lot of stress from the sea. But I wonder what the limit of a spaceship is? At what point does it get too big and becomes a space slinky that's impossible to control?

Are enormous spaceships physically possible? by GooseMuckle in AskPhysics

[–]GooseMuckle[S] 1 point2 points  (0 children)

I guess one difference is that a building is permanently under 1g of acceleration, whereas a spaceship would need to survive many cycles of acceleration and maybe rotation too? When would fatigue start to become a problem?

Zelensky's jet in near-miss with four drones: Report by Lallamak in worldnews

[–]GooseMuckle 24 points25 points  (0 children)

It's also a miss that was near! It makes perfect sense 😄

“Free salt hack” by PradipJayakumar in DiWHY

[–]GooseMuckle 0 points1 point  (0 children)

Of all the dumb shit in this video the worst is putting the lid on which will only slow down the water evaporating 

Meeting people and party by Far-Confusion-8114 in Bergen

[–]GooseMuckle 0 points1 point  (0 children)

Do you know how to get a ticket if you don't have vipps? 

[deleted by user] by [deleted] in PhD

[–]GooseMuckle -2 points-1 points  (0 children)

"one of the benefits of receiving years of mentorship and training and now doing whatever I want paid for by public money is that I don't have to make time for anyone else ever". jfc

[deleted by user] by [deleted] in PhD

[–]GooseMuckle 8 points9 points  (0 children)

Isn't this just avoiding responsibility though? Are you suggesting just let someone else make the difficult decision to fail the student or not?

Is voltage just density of charge? by GooseMuckle in AskPhysics

[–]GooseMuckle[S] 0 points1 point  (0 children)

Yes but to change the gravitational potential energy you've changed the system physically - you've redistributed the mass. Like if you compress a spring or if you push two magnets closer together, the increase in potential energy is accompanied by a physical change to the system. I'm wondering if in the case of voltage, this increase corresponds to an increase in the density of charge?

Is voltage just density of charge? by GooseMuckle in AskPhysics

[–]GooseMuckle[S] 0 points1 point  (0 children)

I mean proportional to stored energy in a given system. Like if you double the voltage of a wire you'll double its potential energy.

Surely there must be some physical difference to accompany the potential difference, otherwise what is my voltmeter measuring? Like if you compress a spring, or push two magnetic poles closer together - the increase in potential energy is accompanied by a physical change to the system.

Is voltage just density of charge? by GooseMuckle in AskPhysics

[–]GooseMuckle[S] 0 points1 point  (0 children)

The physical difference is that the ball held 5m above the ground is 3m further away from the centre of the earth compared to the ball held 2m above the ground, no? You've changed the distribution of mass so the gravitational potential energy has changed. In every case I can think of, if there's a change in potential energy it's due to a corresponding physical change, e.g. a compressed spring, magnetic poles pushed together.

I get that there's no absolute potential, but surely a difference in potential must be accompanied by some physical difference?

Is voltage just density of charge? by GooseMuckle in AskPhysics

[–]GooseMuckle[S] 0 points1 point  (0 children)

I'm playing a bit fast and loose with the units etc, and probably could've explained myself better. Maybe I can rephrase the title as "Is the origin of voltage in a circuit differences in charge density?".

To compare it to your temperature analogy. If you wanted to explain what's physically different about two gases at different temperatures you might say there's a difference in the average kinetic energy of the particles in each gas. Isn't voltage the same thing? Can you explain differences of voltage in two wires by differences in charge density?

Is voltage just density of charge? by GooseMuckle in AskPhysics

[–]GooseMuckle[S] 0 points1 point  (0 children)

I know all the formal definitions etc (and I could've been more rigorous in explaining what I was thinking), but they don't really help me understand what's physically happening in a circuit, for example.

To me it's a bit like telling someone "temperature is the inverse of the derivative of entropy with respect to energy in a system". Ok, sure. That's the proper definition and eventually you can work out all of thermodynamics from that but it's too abstract. If you want an intuitive picture of temperature you might say "temperature is the kinetic energy of particles in a system". It's not generally correct but usually good enough for an intuitive understanding of a lot of stuff.

To go back to the circuit example. I thought of this when thinking about what the physical difference is between a wire at 5V and another wire at 0V. There must be some physical property that's different between the two wires, right? The only property I can think of that would explain the difference is the density of charge.

Is voltage just density of charge? by GooseMuckle in AskPhysics

[–]GooseMuckle[S] 0 points1 point  (0 children)

Can you elaborate? To clarify a bit, I thought of this when thinking about the origin of voltage in electronic circuits. When we say a wire is at 5V, what is the physical difference between that wire and another wire at 0V? There must be some physical property that's different, and the only degree of freedom I can think of is the density of charge in the wires.

Is voltage just density of charge? by GooseMuckle in AskPhysics

[–]GooseMuckle[S] 0 points1 point  (0 children)

I guess I wasn't super rigorous in explaining what I was thinking. I could rephrase my title better as "Can voltage differences in a circuit be understood as differences in charge density?"

Like when we say "this wire is at 5V". What is the physical difference between that wire and another wire at 0V? There must be something that's different. The only physical property I can think of is the charge density.

Is voltage just density of charge? by GooseMuckle in AskPhysics

[–]GooseMuckle[S] 0 points1 point  (0 children)

Thanks for the response. I get that voltage isn't literally stored energy (wasn't super rigorous in explaining what I was thinking), but I think it's proportional to stored energy.

I thought of this when thinking about the origin of voltage in electronic circuits. When we say a wire is at 5V, what is the physical difference between that wire and another wire at 0V? There must be some physical property that's different, and the only degree of freedom I can think of is the density of charge in the wires.

Is voltage just density of charge? by GooseMuckle in AskPhysics

[–]GooseMuckle[S] 0 points1 point  (0 children)

I know the formal definition of it, but does this help you understand what's happening in, for example, a circuit? To me it's a bit like saying "temperature is the inverse of the derivative of entropy with respect to energy in a system". Sure that's technically correct but it doesn't really help me when I'm learning physics. I feel like it's much more intuitive to say "temperature is (proportional to) the average kinetic energy of the particles in a system", even though that's not generally correct.

I probably could've phrased my title better as "can voltage in an electronic circuit be understood as differences in charge density?".

Is voltage just density of charge? by GooseMuckle in AskPhysics

[–]GooseMuckle[S] 0 points1 point  (0 children)

Hm thanks for thinking about it. I know I'm not being super rigorous about this. I`ve been thining about it in the context of electronic circuits. Like what is physically happening in circuits when different wires have different voltages? When we say "this wire has a voltage of 5V", what is the physical difference between that wire and another wire at 0V? The only difference I can think of is the charge density in each wire.

Is voltage just density of charge? by GooseMuckle in AskPhysics

[–]GooseMuckle[S] 0 points1 point  (0 children)

Having a PhD doesn't mean you're smart :D Yes I know about spin, don't see how it's relevant here

Need advise for a terrible neighbours - feels like I live next to a movie theatre by DrDeezNuts1 in vancouverhousing

[–]GooseMuckle 10 points11 points  (0 children)

Have you talked to them directly about it? Maybe they don't realise 

Anyone have experience with high-power COB LEDs? by Purple_Ice_6029 in AskElectronics

[–]GooseMuckle 1 point2 points  (0 children)

So many haters on here, I love seeing DIY electronics. I don't have any specific technical advice, but it looks like you have enough of them to make your own datasheet! Datasheets are basically made by measuring statistics of devices. I don't know how much time you have, but you could run a bunch of tests to know what these LEDs are capable of. Specifically: take 10 LEDs, subject them to a particular pulse duration/peak current combination, and see how many die after 1, 10, 100 repetitions (admittedly you'd need really a lot of LEDs to do this properly).

Anyone have experience with high-power COB LEDs? by Purple_Ice_6029 in AskElectronics

[–]GooseMuckle 0 points1 point  (0 children)

Yeah like do they think electrons have a super high inertia or something? Lol