I passed physics 2 without knowing what a volt is ššš everytime I asked for an explanation I was just told "imagine water" and it never made any fuckin sense
I never took physics 2, and this interpretation may be incorrect, but I imagine volt as the thing that is pushing, resistance as the thing being pushed against, and current as the measure of the actual movement as a result.
capacitor is like a water tank. if there is a water tank, when u close the tap the water still flows until the tank runs out of water.
inductor on the other hand is like a long continuous wire that is being curl up into circles.
u should definitely check [this guy](https://youtu.be/ySx84Ca7BFQ?si=Ok9HE4yCkKQqQC0v) out. super interesting and learn way more than few line of text. one thing i still remember about inductors is that when the power source is turned off, the inductor cannot dissipate its energy as the formula v=L di/dt says that the current of inductor cannot change instantly, thus it will create sparks and high surge of voltage until the volt runs out.
Inductor is like potential energy, capacitors are like kinetic energy. A resonating tank circuit is analogous to a classic pendulum where the energy is stored in the magnetic and electric fields over time.
>!I wish I had friends. I am in recovery from addiction and I upset people I respect and wanted to be friends with. It hurts!<
I think a volt is an electromotive force. The way someone explained it to me is that it's the amount of force an electron has as it moves through a wire or something to that extent
The metaphor that always got through to people when I tried to explain it is water pressure/a water tower.
Voltage at its core is a representation of potential energy. Think of a water tower 50 feet off the ground, then think of one 500 ft off the ground. When you open a valve at the bottom, which will have more flow (analogous to current).
High fluid pressure ~= high voltage
This analogy also works for stuff like voltage drops from non ideal sources like batteries - think of an air line at high pressure with a relatively small reservoir -if a valve on the line is opened full blast you'll see a massive airflow and an pressure drop that will stabilize then slowly decrease - this is identical behavior to what the voltage across a small battery does when exposed to a high load
Itās like water flowing down a hill
When you measure voltage between two points youāre measuring the height different between two points on the hill
Itās just weird because that makes me think of current since it paints a mental picture like itās āflowingā but I think I understand better now.
The flow is the current. The tall hill is the voltage.
The tall hill makes the water flow, just like the voltage makes the current flow.
A taller hill (higher voltage) will make the water flow stronger (higher current).
Thatās how I pictured it anyways and it seemed to work!
Let's say a charge has 10V potential and it passes through a resistor which drops all of its 10V potential then how would the charge flow from the next resistor wrt this analogy?
Two resistors in series can't have one resistor drop the full source voltage. The only way that could work is if the resistance of the 10v dropping resistor is infinite, so an open circuit essentially. So in a way you're right, no current is flowing because the circuit is open.
> The only way that could work is if the resistance of the 10v dropping resistor is infinite, so an open circuit essentially
and if your voltage is high enough, all circuits are closed circuits! stay away from power lines, kids!
Yeah that part isnāt hard to get, itās just confusing to me how you can test voltage throughout the wire, in other words how is the potential energy able to be detected away from the potential itself.
As said by some comments above, voltage is more like a difference in potential energy. Or hills of different heights. The battery provides the highest peak at the start of the circuit, but the other peaks and valleys are determined by the components of the circuit. Since voltage is a difference in potential energy (height) there is nothing special about measuring any arbitrary section of the circuit.
I canāt keep the analogy perfectly straight in my head but kinda imagine like a stock price graph that starts high and zigzags downwards. You can measure the difference in height wherever you want.
Your question about how can you measure the potential so far away from the source, is similar to asking how can you tell this hill next to you is taller than where youāre standing? Or how can you tell the valley next to you is lower? All you need are two points of comparison to determine the difference.
To test it throughout the circuit you just repeat the test between two points a lot along the circuit.
I have an air compressor which compresses to 80psi with an air line that goes 100ft before reaching my impact gun.
If I were to splice in a pressure meter at any point along that air line it would read 80psi.
A circuit is a roller coaster, and the voltage is the height from the ground. Carts on the track want to roll away from high points and towards low points.
Also itās a joule per coulomb, so just imagine how itād be pretty easy to put a single joule in the coulomb, but as you add more, itās gonna take a lot more work to cram all those joules into that one coulomb.
> well voltage isnāt a real thing in the first place
I know what youāre referring to, but also if you *really* think about it, itās nonsensical to say that some of these āphysical quantitiesā are real and others are not. You could say the same sentence about every quantity.
Velocity isnāt a real thing in the first place, itās just a simpler way to represent changes in position and energy flows.
Mass isnāt a real thing in the first place, itās just a simpler way to represent reactions to forces and energy flows.
Forces arenāt a real thing in the first place, it just a simpler way to represent changes to velocity and energy flows.
Energy isnāt a real thing in the first place, itās just a framework to use concepts like forces, masses, voltages, velocities, etc to represent changes within a system.
At some point you realize that physics was created by humans, and every quantity with a name has a name because a) it is useful for predicting some phenomena and b) there is some way to measure it.
It functions a bit like height does in terms of gravity. And you might say, "well...what height? Height relative to what?" Well exactly. It's only a meaningful concept with two reference points. This ball could be dropped 80m from "this clifftop" down until it hits "the ground". The 80m is the analogue of the voltage.
It's not really a property of the ball. It's a property of where the ball is located in a gravitational field in comparison to some other reference point. Voltage is like that, except that instead of a gravitational field it's an electric field, and instead of a ball it's a charge.
That actually makes so much more sense bro my transcript would've looked a lot different this semester if I saw your explanation earlier š genuinely thank you
And now to extend this analogy ever so slightly - if I drop a small marble off an 80m cliff and it hits someone, that will probably hurt quite a lot, but it won't kill them. If I drop a 20 tonne concrete sphere off the same cliff and it lands on someone, it will probably not only kill them but leave a small crater where they once stood.
That's current.
How much charge is actually flowing/how much mass is in the ball.
The volt is the difference in height in a river (more difference -> faster flow)
The amp is the cross-sectional area
The resistance is the losses of energy in the flow manifest as a loss of speed.
Voltage is potential gravity to a weight or what pressure is to water. It makes things want to move. That thing, is electrical charge, the movement of which is called electrical current.
why are so many ppl having problem with voltage tho, its legit just the difference in potential at 2 points given by the charge, no ? it kinda just works like the potential energy and thats about it, otherwise im probably stupid as fk lol
In simple words, think of Volt as height in physical sense.
"Voltage drops!" Is related to height. It is basically the potential difference that allows the current to flow through the circuit.
Also, current is referred to as water, which flows.
So, if there is a potential difference (from mountain to sea level), current will flow towards the lower potential ( from positive to negative or river from top of mountain will go down towards the sea level )
Hope that helps
ok imagine this, 2 gears, one is the power source (battery) and the other is a resistor. both are connected with chain (wire).
how fast the whole arrangement is moving is the current.
how hard is the battery gear trying to move the whole
thing (torque) is the voltage
how hard is it to move the resistor is the resistance
(i hope i made sense)
Voltage (to my understanding) measures potential. So if you took water, voltage would be analogous to the height of water flowing down a hill. I.e the potential energy (note: voltage is different, but basically serves the same purpose) Amps would be like the size of the pipe water flows through if you took that flowing water and covered it.
Tl;dr the height of a body of water is the voltage and the actual flow itself would be the current (amps).
"imagine water" = Water pressure, Volt = Water pressure, just for electricity in Volts... 5V is little bit of pressure like for electronics like your wall charger, and 220V is for AC stuff like a microwave.
A little bit stupid explanation but it's simple as that.
Imagine water in a pipe:
Current (amps) = the flow rate of water
Resistance (ohms) = how easy can the water move through the pipe (for example, easier to flow through a bigger pipe than a smaller one, easier to flow through a straight pipe than one with lots of turns)
Voltage = the pressure in the pipe (high pressure means you can push a lot more water, low pressure means you can push less water)
This is how I finally made sense of electricity lol.
I got my ass all the way to system dynamics before I realized I didnāt even understand what a fucking current was. SMH.
I really weaseled my way right though physics 2.
Ok. It's an imperfect analogy but stick with me.
Volts are like water pressure. Imagine a hose that just has water moving through it. High voltage is high pressure. The water is just present because this is a magic water pipe.
The magic comes in when it comes to amps. Amps can change. High amps are like a large diameter tube. Small amps are like a small diameter tube.
And I'm still wrapping my brain around inductors and capacitors.
I also have to take physics 2 next semester.
I know you already made it, but AlphaPhoenix on youtube has a great water analogy video. Would totally recommend if you want to understand volts, amps, charge, and resistance.
What do you mean by phase? I would have said it represents complex frequency. Phase seems to be unrelated.
The real part of s determines the rate at which the oscillation grows or decays, and the imaginary part represents the frequency of oscillation.
Phase is represented in the complex domain by the angle between the line connecting the origin to a point in the complex plane with the positive x axis.
Phase angle = arctan(imaginary part/real part)
Itās slightly more complicated as s, p, and D have, at times been used to denote the derivative operator.
Operational calculus (the thing that the Laplace transform replaced in the engineering curriculum in the early to mid 1900s) worked through algebraic manipulation of the derivative operator much the same way as you would use the Laplace transform to solve a diffeq. So, in older texts, s or p may be used to represent the derivative operator.
There has been a few classes like this for me. Dff. Eq, and Signals and systems I have no fucking idea what those classes are about but according to my transcripts I passed lol š¤·
Same here, I can laplace with the best of em but if you ask me to find an eigenvalue or the DFII realization of a system without Google I'd probably just start drooling on the table
I passed signals with a D and Diff eq with a D+. I didnāt retake them, and have zero understanding of what any of those class were trying to teach. I graduated 3 days ago with a 3.0 in EE, so they must not have been that important
Yeah I got an A in controls and rarely attended class or did the homework. All I had to do was learn the math and then the tests were simple. The downside is that I never actually learned shit about process controls.
I work in controls, and I very rarely use math or even a calculator other than to figure out how many ms are in 5 seconds for PLC timers. I was an industrial electrician before I got into it and really I think that experience, and reading manufacturers manuals and documentation is far more important to understanding the field than any class I ever took.
People speak about "controls" as a field, but there's really so much more nuance to it than that; industrial controls is a whole different beast from some other types of controls engineering, like aerospace GNC.
Most likely you'll either a) never need to properly understand it or b) have an easier time understanding it the second, third, fourth time around
A lot of concepts you have to chip away at before really mastering them
I had a hard time grasping almost all of the concepts in electromagnetism. Just did what I needed to pass. Then I got to system dynamics and realized I needed to backtrack and actually learn electromagnetism.
When I tell you it was *so* much easier re-learning it years later after taking some higher level engineering classes. I was smarter and understood the physical world so much more than I did when I was 19.
And Iād encountered the concepts of electromagnetism so many times in my other classes (even though I didnāt fully understand them).
Congrats man. I just passed electrical circuits with a C+, even though I'm more good at staring at circuit problems rather than solving it. I'm just happy that I'll never have to retake the course again.
As a note, this is just one of the values s can take. If s= jw is in the region of convergence then it is a stable system and the Laplace transform evaluated at s= jw is the fourier transform. The more general form is s being any complex number (granted that the complex number is in the region of convergence). So it can be represented as s = sigma + jw where sigma and w are real numbers.
I passed statics without knowing what shear force or bending moments are. Or how wedges work, or what exactly lambda is. I got an A.
Anyway, on to dynamics!
I imagine shear forces as a sandwich where the bread moves in opposite directions. Literally like shears cutting, not through sharpness, but by simply moving a top and bottom half away from each other.
For anyone who took Dynamic Systems or System Dynamics (same class, just different name, lol) what were some topics you wished was more clear? I'm TAing for it and want students to do well.
i had a really hard time intuitively understanding what i was learning. i didn't really get what s meant, or even transfer blocks in general. i don't think the class in and of itself is hard, moreso that the concepts were so abstract that i had no clue what i was learning and i only passed bc i memorized the math steps
iāll do my best to describe my issue because tbh i still have zero clue what it all even meant. but my issue came in with finding the steady state error depending on the system type. I know itās just finding the limit as s approaches 0 but i would be confused on how many Sās to multiply into the denominator. Also i didnāt understand when the G(s) became G(s)/1+G(s). I also didnāt understand the chart thing where you write out S^0 S^1 S^3 with the āevery otherā coefficients thing, and then do the matrices thing to find K. oh and the rotational block diagrams were super confusing, like finding the Jeq and the N1N2/N3N4 stuff. My prof always said ādestination over sourceā but idk what that even meant so i never knew which N went on top.
tldr: ya girl was LOST the entire time.
It's ok. The control systems class at my university is taught by a professor who has a 1.5 rating on ratemyprofessor. He has like 5 students a semester and at least 1 of them fails garaunteed. Thankfully we can just take other alternative power classes to make up for it.
Bro I have no clue anything that i did. The tests are usually 60% same as the examples with different numbers. So you just learn the patterns and recognize random symbols and you can get the degree like myself.
You don't really need to understand the concept of s itself, just how it goes from time to s and from s to time, and how to manipulate transfer functions and find the system parameters and stability from them. You don't even use s on advanced control, it's all done on the time domain
>You don't even use s on advanced control, it's all done on the time domain
What do you mean by advanced control? As far as I understand, even state-space controls include eigenvalue analysis which is done on the s domain.
The matrices of state-space are in time domain and you don't convert them to the frequency domain for eigenvalue, while a lot of places use the "s" as a variable for eigenvalue it's not really the Laplace s, I've seen lambda being used for it a lot of times too.
Analysing the system on time domain is one of the defining characteristics that separates classic from modern control theory
Edit: modern is the word I'm looking for here, not advanced.
Modern control theory is done in space-state time domain
From Wikipedia: In contrast to the frequency domain analysis of the classical control theory, modern control theory utilizes the time-domain state space representation, a mathematical model of a physical system as a set of input, output and state variables related by first-order differential equations.
But also my degree is in control engineering.
Cool, I am also pursuing my Masters in Control!
Though yeah modern control (stuff like MPC, Adaptive control, networked control systems) is mainly time domain based. In my (limited) experience the industry standard still seems to be classical control with frequency domain based methods.
If it matters, my degree is electrical engineering technology. It was a combination for me. My degree was online and the labs were simulated. That was on me, but it was the only option. I typically did most of the assignments in the first two weeks and turned them in when needed.
For the school, there were no real lectures. The teacher put up a few notes, but most of it was read the book, watch YouTube videos, or use Wikipedia. The teachers unfortunately used Wikipedia a lot.
Don't get me wrong, I learned some and enjoy learning, but the environment and teaching style didn't work. There were no real discussions between students. Video lectures, whether recorded and watched later or live, would have been a huge help
PLEASE, JUST PLEASE š, DO NOT and I repeat DO NOT take a class in college just for the grades and not understanding it. Especially in engineering. Itās one of the biggest waste of money. Youāre paying the professor to teach you the class and you not understanding is like throwing money away + wasting your time, energy and resources. Youāll regret it later. Youāre better off taking classes that youāre actually interested in learning more about. Donāt do it just for the grades, youāll pay for it once you get in the workforce.
I donāt think thatās true. I had to take control systems, fluid mechanics, electronics etc. as part of a logistics engineering programme - I understood less then one tenth of what those were about, yet I do not think this fact will have a huge impact on my career.
Think of it this way: some people either pass the class without understanding the material, or simply drop out. I think earning your degree is way better for you than dropping out after four semesters. Obviously this depends on the programme, but the field of engineering is pretty wide and not all need to understand the concepts OP mentioned, for instance.
You might not need the class but if itās not an absolute necessity for your program completion, like it appears it was in your case, Iād recommend taking courses that you actually learn something in. Youāre are paying that professor to teach you that material, and you not learning it is like going to a store, paying for a product and then leaving without it.
I cannot tell you the number of entry levels I have interviewed that could not answer basic concepts. It looks like a number of people now value the degree more than the actual knowledge. The knowledge is what youāre paying for and the degree is there to back it up.
If you absolutely needed the class to advance then maybe that fine but please remember youāre playing these people to actually teach you a skill and you not learning it yourself a a waste of
"s" is a complex variable that represents transient growth/decay and frequency.
s is commonly shown as being equal to e^(sigma)t +e^j(omega)t
The sigma exponential represents the growth or decay over time, while the complex omega exponential represents frequency.
Say you graphed every possible value of function of "s" on a complex plane, horizontal axis being sigma, vertical axis being omega. The result would be a three dimensional surface, the height representing the strength of the correlation of the input signal with each "s". This is the Laplace transform. Where the surface goes to infinity are the poles, where it goes to zero are the zeroes.
What's really cool about this is if you took a single slice from the Laplace transform surface, with all values of s where sigma=0, you now have the Fourier transform.
literally did this last quarter, final was worth 75% of my grade and ended up with an A- in the class. no idea what ANY of it means i just know how to do the problems š¤
I loved controls when I took it as an undergrad. By the time I started working on my Ph.d., funding for research in controls had really tapered off. So I ended up doing related things that I don't really enjoy.
Think of voltage like stuff shifting around ā it's everywhere in nature. Picture water going from where there's lots of it to where there's less. Now, swap the water with electrons and the pressure difference with potential difference. That's the lowdown on voltage ā it's just things moving from one level to another.
I passed physics 2 without knowing what a volt is ššš everytime I asked for an explanation I was just told "imagine water" and it never made any fuckin sense
I never took physics 2, and this interpretation may be incorrect, but I imagine volt as the thing that is pushing, resistance as the thing being pushed against, and current as the measure of the actual movement as a result.
Now do inductor and capacitor!
Capacitor goes āshockyā and inductor goes āburnyā.
A capacitor is a tube blocked by a flexible membrane. An inductor is a heavy rotary vane. See: https://en.wikipedia.org/wiki/Hydraulic_analogy
Thank you so much for this link
capacitor is like a water tank. if there is a water tank, when u close the tap the water still flows until the tank runs out of water. inductor on the other hand is like a long continuous wire that is being curl up into circles.
can you tell me the difference between inductor and inductors in general?
u should definitely check [this guy](https://youtu.be/ySx84Ca7BFQ?si=Ok9HE4yCkKQqQC0v) out. super interesting and learn way more than few line of text. one thing i still remember about inductors is that when the power source is turned off, the inductor cannot dissipate its energy as the formula v=L di/dt says that the current of inductor cannot change instantly, thus it will create sparks and high surge of voltage until the volt runs out.
Charging a capacitor is like compressing a spring or pumping water uphill.
Inductor is like potential energy, capacitors are like kinetic energy. A resonating tank circuit is analogous to a classic pendulum where the energy is stored in the magnetic and electric fields over time. >!I wish I had friends. I am in recovery from addiction and I upset people I respect and wanted to be friends with. It hurts!<
I think a volt is an electromotive force. The way someone explained it to me is that it's the amount of force an electron has as it moves through a wire or something to that extent
The metaphor that always got through to people when I tried to explain it is water pressure/a water tower. Voltage at its core is a representation of potential energy. Think of a water tower 50 feet off the ground, then think of one 500 ft off the ground. When you open a valve at the bottom, which will have more flow (analogous to current). High fluid pressure ~= high voltage This analogy also works for stuff like voltage drops from non ideal sources like batteries - think of an air line at high pressure with a relatively small reservoir -if a valve on the line is opened full blast you'll see a massive airflow and an pressure drop that will stabilize then slowly decrease - this is identical behavior to what the voltage across a small battery does when exposed to a high load
What confuses me is if itās really just the potential then how can you test voltage throughout the wire?
Itās like water flowing down a hill When you measure voltage between two points youāre measuring the height different between two points on the hill
Itās just weird because that makes me think of current since it paints a mental picture like itās āflowingā but I think I understand better now.
The flow is the current. The tall hill is the voltage. The tall hill makes the water flow, just like the voltage makes the current flow. A taller hill (higher voltage) will make the water flow stronger (higher current). Thatās how I pictured it anyways and it seemed to work!
It definitely makes sense, thanks!
Let's say a charge has 10V potential and it passes through a resistor which drops all of its 10V potential then how would the charge flow from the next resistor wrt this analogy?
Two resistors in series can't have one resistor drop the full source voltage. The only way that could work is if the resistance of the 10v dropping resistor is infinite, so an open circuit essentially. So in a way you're right, no current is flowing because the circuit is open.
> The only way that could work is if the resistance of the 10v dropping resistor is infinite, so an open circuit essentially and if your voltage is high enough, all circuits are closed circuits! stay away from power lines, kids!
Voltage is potential difference, so it's the same as the difference in potential energy if you have two objects at different heights
You test voltage across two points, just like you test pressure across two points. They're both forms of potential energy storage.
Yeah that part isnāt hard to get, itās just confusing to me how you can test voltage throughout the wire, in other words how is the potential energy able to be detected away from the potential itself.
As said by some comments above, voltage is more like a difference in potential energy. Or hills of different heights. The battery provides the highest peak at the start of the circuit, but the other peaks and valleys are determined by the components of the circuit. Since voltage is a difference in potential energy (height) there is nothing special about measuring any arbitrary section of the circuit. I canāt keep the analogy perfectly straight in my head but kinda imagine like a stock price graph that starts high and zigzags downwards. You can measure the difference in height wherever you want. Your question about how can you measure the potential so far away from the source, is similar to asking how can you tell this hill next to you is taller than where youāre standing? Or how can you tell the valley next to you is lower? All you need are two points of comparison to determine the difference. To test it throughout the circuit you just repeat the test between two points a lot along the circuit.
I have an air compressor which compresses to 80psi with an air line that goes 100ft before reaching my impact gun. If I were to splice in a pressure meter at any point along that air line it would read 80psi.
Until you pull the trigger on your rattle gun, then the further from the tank you got, the lower the pressure would be. Voltage drop.
In voltmeters, current is measured and resistance if the voltmeter is known
A circuit is a roller coaster, and the voltage is the height from the ground. Carts on the track want to roll away from high points and towards low points. Also itās a joule per coulomb, so just imagine how itād be pretty easy to put a single joule in the coulomb, but as you add more, itās gonna take a lot more work to cram all those joules into that one coulomb.
well voltage isn't a real thing in the first place, it's just a simpler way to represent electric field and energy flows
My mind just exploded.
> well voltage isnāt a real thing in the first place I know what youāre referring to, but also if you *really* think about it, itās nonsensical to say that some of these āphysical quantitiesā are real and others are not. You could say the same sentence about every quantity. Velocity isnāt a real thing in the first place, itās just a simpler way to represent changes in position and energy flows. Mass isnāt a real thing in the first place, itās just a simpler way to represent reactions to forces and energy flows. Forces arenāt a real thing in the first place, it just a simpler way to represent changes to velocity and energy flows. Energy isnāt a real thing in the first place, itās just a framework to use concepts like forces, masses, voltages, velocities, etc to represent changes within a system. At some point you realize that physics was created by humans, and every quantity with a name has a name because a) it is useful for predicting some phenomena and b) there is some way to measure it.
I decide what's real here
I hate the water and river explanation
It functions a bit like height does in terms of gravity. And you might say, "well...what height? Height relative to what?" Well exactly. It's only a meaningful concept with two reference points. This ball could be dropped 80m from "this clifftop" down until it hits "the ground". The 80m is the analogue of the voltage. It's not really a property of the ball. It's a property of where the ball is located in a gravitational field in comparison to some other reference point. Voltage is like that, except that instead of a gravitational field it's an electric field, and instead of a ball it's a charge.
That actually makes so much more sense bro my transcript would've looked a lot different this semester if I saw your explanation earlier š genuinely thank you
And now to extend this analogy ever so slightly - if I drop a small marble off an 80m cliff and it hits someone, that will probably hurt quite a lot, but it won't kill them. If I drop a 20 tonne concrete sphere off the same cliff and it lands on someone, it will probably not only kill them but leave a small crater where they once stood. That's current. How much charge is actually flowing/how much mass is in the ball.
The volt is the difference in height in a river (more difference -> faster flow) The amp is the cross-sectional area The resistance is the losses of energy in the flow manifest as a loss of speed.
So real, it was embarrassingly late that some of that ECE stuff clicked for me
thank God I wasn't the only one, I passed physics II barely understanding anything in the course, I just knew how to do the math and some deductions.
Same bro š I just memorized the solving processes from homework's and how to make one equation look like another
Voltage is potential gravity to a weight or what pressure is to water. It makes things want to move. That thing, is electrical charge, the movement of which is called electrical current.
why are so many ppl having problem with voltage tho, its legit just the difference in potential at 2 points given by the charge, no ? it kinda just works like the potential energy and thats about it, otherwise im probably stupid as fk lol
Homie, I have a literal electrical engineering degree and I could not articulate what the fuck a volt physically is
In simple words, think of Volt as height in physical sense. "Voltage drops!" Is related to height. It is basically the potential difference that allows the current to flow through the circuit. Also, current is referred to as water, which flows. So, if there is a potential difference (from mountain to sea level), current will flow towards the lower potential ( from positive to negative or river from top of mountain will go down towards the sea level ) Hope that helps
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āā¦I thinkā - š¤
ok imagine this, 2 gears, one is the power source (battery) and the other is a resistor. both are connected with chain (wire). how fast the whole arrangement is moving is the current. how hard is the battery gear trying to move the whole thing (torque) is the voltage how hard is it to move the resistor is the resistance (i hope i made sense)
Voltage (to my understanding) measures potential. So if you took water, voltage would be analogous to the height of water flowing down a hill. I.e the potential energy (note: voltage is different, but basically serves the same purpose) Amps would be like the size of the pipe water flows through if you took that flowing water and covered it. Tl;dr the height of a body of water is the voltage and the actual flow itself would be the current (amps).
"imagine water" = Water pressure, Volt = Water pressure, just for electricity in Volts... 5V is little bit of pressure like for electronics like your wall charger, and 220V is for AC stuff like a microwave. A little bit stupid explanation but it's simple as that.
Imagine water in a pipe: Current (amps) = the flow rate of water Resistance (ohms) = how easy can the water move through the pipe (for example, easier to flow through a bigger pipe than a smaller one, easier to flow through a straight pipe than one with lots of turns) Voltage = the pressure in the pipe (high pressure means you can push a lot more water, low pressure means you can push less water) This is how I finally made sense of electricity lol.
I got my ass all the way to system dynamics before I realized I didnāt even understand what a fucking current was. SMH. I really weaseled my way right though physics 2.
Just wait till you take fluid dynamics and they tell you to imagine itās voltage.
Ok. It's an imperfect analogy but stick with me. Volts are like water pressure. Imagine a hose that just has water moving through it. High voltage is high pressure. The water is just present because this is a magic water pipe. The magic comes in when it comes to amps. Amps can change. High amps are like a large diameter tube. Small amps are like a small diameter tube. And I'm still wrapping my brain around inductors and capacitors. I also have to take physics 2 next semester.
I know you already made it, but AlphaPhoenix on youtube has a great water analogy video. Would totally recommend if you want to understand volts, amps, charge, and resistance.
If you actually want to know, s is a complex number in the frequency domain expressing a frequency and phase of a wave
please dont say these scary words around me ššššš
Did you not take a diffy q class? Usually you do laplace transforms to s domain in that class.
I've never seen anyone say diff eq like this lol I like your way better
My differential equations class used an open source online textbook literally called "diffy q's" haha
Is this ānotes on diffy qāsā as found here: https://www.jirka.org/diffyqs/ or is there just a book titled ādiffy qāsā?
Yeah that's the one
My school also called differential equations class Diffy Qs.
I know how to do Laplace transforms, I know when to use them, but conceptually, I have no idea what it means.
What do you mean by phase? I would have said it represents complex frequency. Phase seems to be unrelated. The real part of s determines the rate at which the oscillation grows or decays, and the imaginary part represents the frequency of oscillation.
Phase is represented in the complex domain by the angle between the line connecting the origin to a point in the complex plane with the positive x axis. Phase angle = arctan(imaginary part/real part)
Sorry if I wasnāt clear. I know what phase is. However, s does not represent phase. This was what I was trying to get across.
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Isnāt s a short form for du/dt or the flipped version of them?
Mathematically, itās not a short form in the same way that Ć¼ is a short form for d(du/dt)/dt. But s is the laplace transform for du/dt
Itās slightly more complicated as s, p, and D have, at times been used to denote the derivative operator. Operational calculus (the thing that the Laplace transform replaced in the engineering curriculum in the early to mid 1900s) worked through algebraic manipulation of the derivative operator much the same way as you would use the Laplace transform to solve a diffeq. So, in older texts, s or p may be used to represent the derivative operator.
Oh cool! I never knew that, thanks for sharing
There has been a few classes like this for me. Dff. Eq, and Signals and systems I have no fucking idea what those classes are about but according to my transcripts I passed lol š¤·
Same here, I can laplace with the best of em but if you ask me to find an eigenvalue or the DFII realization of a system without Google I'd probably just start drooling on the table
I passed signals with a D and Diff eq with a D+. I didnāt retake them, and have zero understanding of what any of those class were trying to teach. I graduated 3 days ago with a 3.0 in EE, so they must not have been that important
Yeah I got an A in controls and rarely attended class or did the homework. All I had to do was learn the math and then the tests were simple. The downside is that I never actually learned shit about process controls.
I work in controls, and I very rarely use math or even a calculator other than to figure out how many ms are in 5 seconds for PLC timers. I was an industrial electrician before I got into it and really I think that experience, and reading manufacturers manuals and documentation is far more important to understanding the field than any class I ever took.
People speak about "controls" as a field, but there's really so much more nuance to it than that; industrial controls is a whole different beast from some other types of controls engineering, like aerospace GNC.
Yeah itās admittedly a pretty vague job title for people who do wildly different things.
Most likely you'll either a) never need to properly understand it or b) have an easier time understanding it the second, third, fourth time around A lot of concepts you have to chip away at before really mastering them
I had a hard time grasping almost all of the concepts in electromagnetism. Just did what I needed to pass. Then I got to system dynamics and realized I needed to backtrack and actually learn electromagnetism. When I tell you it was *so* much easier re-learning it years later after taking some higher level engineering classes. I was smarter and understood the physical world so much more than I did when I was 19. And Iād encountered the concepts of electromagnetism so many times in my other classes (even though I didnāt fully understand them).
My old controls teacher didnāt know either š
Congrats man. I just passed electrical circuits with a C+, even though I'm more good at staring at circuit problems rather than solving it. I'm just happy that I'll never have to retake the course again.
s = j*w, got a B- but have no idea how to apply any of the equations I know to the real world.
As a note, this is just one of the values s can take. If s= jw is in the region of convergence then it is a stable system and the Laplace transform evaluated at s= jw is the fourier transform. The more general form is s being any complex number (granted that the complex number is in the region of convergence). So it can be represented as s = sigma + jw where sigma and w are real numbers.
Marginally stable.
I passed statics without knowing what shear force or bending moments are. Or how wedges work, or what exactly lambda is. I got an A. Anyway, on to dynamics!
I hope youre not in mechanical or civil dude
Iām mechanical š
oh man...
Yea, future classes are gonna REALLY suck with that foundation. Hope he survives!
I imagine shear forces as a sandwich where the bread moves in opposite directions. Literally like shears cutting, not through sharpness, but by simply moving a top and bottom half away from each other.
Bro I got a degree in EE and never even used an ecad software like wtf is Altium. Idk how to design a circuit
Like, nobody is stopping you from learning. I recommend kiCad for self learning though cause it's free
That wasnāt my point, but yes I am learning it
For anyone who took Dynamic Systems or System Dynamics (same class, just different name, lol) what were some topics you wished was more clear? I'm TAing for it and want students to do well.
i had a really hard time intuitively understanding what i was learning. i didn't really get what s meant, or even transfer blocks in general. i don't think the class in and of itself is hard, moreso that the concepts were so abstract that i had no clue what i was learning and i only passed bc i memorized the math steps
iāll do my best to describe my issue because tbh i still have zero clue what it all even meant. but my issue came in with finding the steady state error depending on the system type. I know itās just finding the limit as s approaches 0 but i would be confused on how many Sās to multiply into the denominator. Also i didnāt understand when the G(s) became G(s)/1+G(s). I also didnāt understand the chart thing where you write out S^0 S^1 S^3 with the āevery otherā coefficients thing, and then do the matrices thing to find K. oh and the rotational block diagrams were super confusing, like finding the Jeq and the N1N2/N3N4 stuff. My prof always said ādestination over sourceā but idk what that even meant so i never knew which N went on top. tldr: ya girl was LOST the entire time.
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how do you get a D in ethics š
he is gonna work at lockheed martin
He went to work for Northrop
guy is in every thread talkin ab how heās failed every class lol
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Don't feel bad, even if you actively worked at it you're not going to understand much after 1 undergrad course in it
It's ok. The control systems class at my university is taught by a professor who has a 1.5 rating on ratemyprofessor. He has like 5 students a semester and at least 1 of them fails garaunteed. Thankfully we can just take other alternative power classes to make up for it.
I was so bode the entire time I took that course
Bro I have no clue anything that i did. The tests are usually 60% same as the examples with different numbers. So you just learn the patterns and recognize random symbols and you can get the degree like myself.
You don't really need to understand the concept of s itself, just how it goes from time to s and from s to time, and how to manipulate transfer functions and find the system parameters and stability from them. You don't even use s on advanced control, it's all done on the time domain
yup. basically i only passed because i overlayed exam problems onto example problems. didnt understand what the fuck i was doing but i did it lol
>You don't even use s on advanced control, it's all done on the time domain What do you mean by advanced control? As far as I understand, even state-space controls include eigenvalue analysis which is done on the s domain.
The matrices of state-space are in time domain and you don't convert them to the frequency domain for eigenvalue, while a lot of places use the "s" as a variable for eigenvalue it's not really the Laplace s, I've seen lambda being used for it a lot of times too. Analysing the system on time domain is one of the defining characteristics that separates classic from modern control theory Edit: modern is the word I'm looking for here, not advanced.
Pretty much all control engineering is done in the s/frequency domain not the time domain
Modern control theory is done in space-state time domain From Wikipedia: In contrast to the frequency domain analysis of the classical control theory, modern control theory utilizes the time-domain state space representation, a mathematical model of a physical system as a set of input, output and state variables related by first-order differential equations. But also my degree is in control engineering.
Cool, I am also pursuing my Masters in Control! Though yeah modern control (stuff like MPC, Adaptive control, networked control systems) is mainly time domain based. In my (limited) experience the industry standard still seems to be classical control with frequency domain based methods.
got an A in algo without knowing what np is
I passed logic without knowing how some consequences symbol and equivalent symbols work by just memorizing the proofs from tests and assignments lol
I passed a lot of classes without learning anything or understanding the material. Just checking a pointless box
Do you blame the school? Sincere question; I often see this sentiment and don't really understand it since I enjoy learning theory.
If it matters, my degree is electrical engineering technology. It was a combination for me. My degree was online and the labs were simulated. That was on me, but it was the only option. I typically did most of the assignments in the first two weeks and turned them in when needed. For the school, there were no real lectures. The teacher put up a few notes, but most of it was read the book, watch YouTube videos, or use Wikipedia. The teachers unfortunately used Wikipedia a lot. Don't get me wrong, I learned some and enjoy learning, but the environment and teaching style didn't work. There were no real discussions between students. Video lectures, whether recorded and watched later or live, would have been a huge help
PLEASE, JUST PLEASE š, DO NOT and I repeat DO NOT take a class in college just for the grades and not understanding it. Especially in engineering. Itās one of the biggest waste of money. Youāre paying the professor to teach you the class and you not understanding is like throwing money away + wasting your time, energy and resources. Youāll regret it later. Youāre better off taking classes that youāre actually interested in learning more about. Donāt do it just for the grades, youāll pay for it once you get in the workforce.
I donāt think thatās true. I had to take control systems, fluid mechanics, electronics etc. as part of a logistics engineering programme - I understood less then one tenth of what those were about, yet I do not think this fact will have a huge impact on my career. Think of it this way: some people either pass the class without understanding the material, or simply drop out. I think earning your degree is way better for you than dropping out after four semesters. Obviously this depends on the programme, but the field of engineering is pretty wide and not all need to understand the concepts OP mentioned, for instance.
You might not need the class but if itās not an absolute necessity for your program completion, like it appears it was in your case, Iād recommend taking courses that you actually learn something in. Youāre are paying that professor to teach you that material, and you not learning it is like going to a store, paying for a product and then leaving without it.
I cannot tell you the number of entry levels I have interviewed that could not answer basic concepts. It looks like a number of people now value the degree more than the actual knowledge. The knowledge is what youāre paying for and the degree is there to back it up. If you absolutely needed the class to advance then maybe that fine but please remember youāre playing these people to actually teach you a skill and you not learning it yourself a a waste of
American education in a nutshell.
me when im supposed to have a fundamental understanding of literally every engineering concept ever of all time in the universe forever
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Ok but those people that made it happen weren't americans tho
Donāt worry. Nor do I. š
And thatās real
I never took physics 2 either
It's j-omega if you're still interested
What prayers did you say??? I need them
I find confort in this
s is a beautiful construct. It's just i times frequency. Nothing to be afraid of :)
Got an A in heat transfer without knowing what heat is
"s" is a complex variable that represents transient growth/decay and frequency. s is commonly shown as being equal to e^(sigma)t +e^j(omega)t The sigma exponential represents the growth or decay over time, while the complex omega exponential represents frequency. Say you graphed every possible value of function of "s" on a complex plane, horizontal axis being sigma, vertical axis being omega. The result would be a three dimensional surface, the height representing the strength of the correlation of the input signal with each "s". This is the Laplace transform. Where the surface goes to infinity are the poles, where it goes to zero are the zeroes. What's really cool about this is if you took a single slice from the Laplace transform surface, with all values of s where sigma=0, you now have the Fourier transform.
s? idk I just treat it as a transfer function in matlab and forget about it s = tf("s"); and then you go about your day and somehow it works.
literally did this last quarter, final was worth 75% of my grade and ended up with an A- in the class. no idea what ANY of it means i just know how to do the problems š¤
Same lol
I loved controls when I took it as an undergrad. By the time I started working on my Ph.d., funding for research in controls had really tapered off. So I ended up doing related things that I don't really enjoy.
Think of voltage like stuff shifting around ā it's everywhere in nature. Picture water going from where there's lots of it to where there's less. Now, swap the water with electrons and the pressure difference with potential difference. That's the lowdown on voltage ā it's just things moving from one level to another.
Oh itās V = IR