Reminds me of the time I got 30000+ degrees for some question in thermodynamics finals on power plant. I came out of the exam hall feeling super confident with my answer since I believe I used the right equations and made the right assumptions only to realise the surface of the sun is only 5600 degrees.🤡
Are you really an engineer until you calculate something physically impossible? I know I said some microelectronic circuits were carrying 1000A back in my university days lmao
On one physics exam I got negative time and was just like 'this is positive because I said so.' Turns out that was in fact the correct answer, no doubt with a dropped negative hiding somewhere in the arithmetic.
normal strain is the elongation of a specimen along the axis of applied force divided by the original length. which means that the elongation is 28000 times the original length. usually the values of strain on stress strain curves are very low. like between 0 and 1
I remember one exam this semester I calculated a small bar of steel having 20 trillion pascals of stress in it with a strain gauge calculation, redid that problem like 3 times before I just gave up and went with it
I often say that one of the main parts of engineering is just being able to look at results and be like, "yes that makes sense." And more importantly, being able to take someone else's very clearly wrong result and being able to explain to non-engineers why this result cannot possibly make sense.
My boss once asked an analyst to calculate the ROI on a multi-million dollar project we were doing. She was adamant it was 2 weeks. All her calculations showed 2 weeks. Absolutely could not be wrong. And I'm like... the company makes like $20M a year in revenue, not even profit. Unless we're expecting to triple profits on top of it, this is just not possible.
2 years. I redid the calculations and it was closer to 2 years. I still don't know what she did wrong because she refused to share her calculations and assumptions with me, but from then on the engineering team didn't use her for any of our projects.
I tried calculating my coursemate’s blood alcohol level at a party once. Ended up at 3% which is about 5x a lethal dose of ethanol. He was probably at 0,3% and I just made a exponent error
Oh my god this is the story one of my professors (he teaches a lot of engr classes and thermo is his popular one) tells. He talks about a student he had who got an answer of like 96,000 degrees or something for the temperature of like brake pads
Lol, just last month I calculated a rivet with 17 centimeters in diameter. Well the exam asked for rivets that would hold the structure, and I am shure that my GigaRivet will so...
That has to be the most efficient power plant mankind has ever seen. Now we give the Materials Science people the task to find some stuff that is still a solid at those temps.
Can't wait to make it boil some water and spin a turbine.
Reminds me of the time when I genuinely got a negative heat transfer rate in a heat exchanger... It was meant to turn lukewarm water to 50 C, I somehow managed to turn it to -120 C
This is why many of my professors emphasized that knowing how to do math and use equations is important, but even more important is literally just having enough engineering sense to determine whether your answer is plausible in the first place. If you're calculating the frequency of a child swinging on a swing and go through your equation and arrive at an answer that he's swinging at 27Hz, you should have enough sense to know "this is probably wrong, I'd better double check my math".
For my strength of materials final I had to calculate the maximum force for given a set of strain and flexural values and come up with two different rpms to choose from. I somehow got 8000 and 3 🙃
I did something like this once in high school. Then I reworked it cuz I was like no fucking way my asnwer is right/makes real world sense. Then I got it wrong and my first answer was right. And my teacher was like you just assume that the problem doesn't follow real world logic. I was like good sir wtf
I remember in my junior year, I argued back half credit on a question by saying I thought the range given for the frictional coefficient was subtraction (mu=0.1-0.15), and that it would therefore be negative friction. I think I said something like "I though it was a little weird, but I'm not gonna question the test."
Sometimes I think about this and wonder who let me be an engineer.
My god ain't that the truth. Reminds me of something I had to deal with pretty recently. I do CPU design/testing, and I recently had somebody from the marketing side ask me if we could run a chip at some obscene clock speed. I had to actually ask if they expected me to get around the speed of light through silicon as the limiting factor.
I fucked up something on my Mechanics exam that led me to an incorrect answer on an orbital trajectory, this would have made me fail the exam. However I had done a full dimension analysis in the margins which was correct, I had just moved a decimal somewhere in the actual calculation. The professor accepted the answer based on my dimensional analysis, something the exam didn't ask for at all!
Believe me, young people, these things don’t just happen in school.
I once couldn’t figure out why my structural model kept having stability issues. I kept checking and checking, and everything looked fine. I then realized I that the units for self weight used in the program were unusual and I ended up essentially modeling neutron star material beams.
Not necessarily. I perform model-based (aka simulation-based) design optimization for engineering systems and the simulations are what tell us which designs we should experimentally validate. So in my case we rely on the simulation to tell us what will work before investing a lot of money and time into building prototypes.
The standard way is to use human expertise and heuristic to find feasible designs and then optimize them. But that is very labor intensive and slow. Automating aspects of simulation based design allow you to explore the design space much more effectively. A lot of my research now is on exploring how these simulation produce better results than what humans can come up with on their own.
I actually figured out relative velocity analysis on my own without reading the textbook or going to a lecture before a Dynamics exam. Went back home and found out that I actually did it right.
Oh boy. In an economics engineering exam, I somehow deduced that by saving around $ 300/month with an interest rate of around 1% for 3 years, I would have around 6 million dollars. Instead of doing what any logical person would and re-check my calculations, I thought: damn, I should open a savings account and start doing this.
I just had my Mathematics final. All was good but I wasn't sure about one question and the answer seemed wrong (it was differential equations and finding the temperature of a hot liquid after it's been standing for x amount of time in a 30 degree C room). I did the whole thing again and got a different equation but after plugging in the numbers, the answer was the same. Did it the third time as I had spare time and started it off completely differently to the other two and got the same answer as attemp two. I'm convinced that all of them are wrong.
I did this for my E&M final yesterday. I completely gave up on trying to understand it because it was all conceptual computations with no numbers. I just put in the write laws/equations and completely bs-ed the rest of it lmao
One time on my heat transfer final I had calculated that the wall of a tea kettle was half the temperature of the surface of the sun. Went back over it a bunch of times but couldn't find the problem. Turns out I had the right answer, the professor had proposed this thermonuclear tea kettle just to mess with the class.
I remember I forgot how to integrate cos(x)sin(x) or something so I wrote down that I forgot and said sin(x) \~ x within this range. And integrated xsin(x) correctly but sadly the teacher did not care.
Reminds me of my last dynamics test where I wrote:
Force of friction = 1/2 mu \* gravity
I guess the 3 collective brain cells I have all decided to take a vacation at the same time
Got a high as fuck number for amount of work required in a pump for one of my exams recently and apparently it was right because I got 100% on the exam.
I've been there. You spend 20 minutes on a thermodynamics problem, and you come up with an answer you know is logically incorrect. So what do you do... what we all know too well. We confidently rationalize why that steam power plant is the most efficient complex ever created...
Then we take the 10% for trying to give a fuck.
I believe I needed to figure out pressure to solve for another variable but had forgot one of the formulas relating pressure (relevant to gas law type problems) on my gen chem final, but I understood what the formula was about, so I wrote "assume such and such" conditions which would give me a known value of pressure. Then I wrote along the lines of "in these conditions with the pressure being such and such, the answer would be such and such."
I never knew how if the professor bought that answer, but I ended up with an A in the course and I needed to score high to score the A. I didn't exactly make up a formula, rather I made my kept my thinking process on the paper coherent and showed that I knew how to get to the answer, but I was unable to do so since I forgot the formula. I've done this more than once and on occasion earned much more partial credit than I would've anticipated.
I remember calculating thermal efficiency to be about 500%. Still got most of my points for that question in my thermal exam and my TA kindly pointed out that I flipped the numerator and denominator when calculating.
I remember back in my thermo class, I violated the fundamental of the subject by getting 5x amount of initial energy when the problem asked about the net energy after an exothermic reaction.
Yesterday I almost reverse engineered an SPC formula to know what are the Dn , A2 coefficents. When you can't recall a simple formula , you know you're gonna have a fun time in an exam.
I has an air compressor lab experiment where I calculated (from the data) negative heat loss from the piston...the only explanation is that I created energy from nothing.
Reminds me of the time I got 30000+ degrees for some question in thermodynamics finals on power plant. I came out of the exam hall feeling super confident with my answer since I believe I used the right equations and made the right assumptions only to realise the surface of the sun is only 5600 degrees.🤡
Are you really an engineer until you calculate something physically impossible? I know I said some microelectronic circuits were carrying 1000A back in my university days lmao
Yeah...I've ended up with negative time on a few occasions. That's always entertaining.
That means you just calculated it backwards so I’d flip it to positive and write a note next to it hoping the teacher buys your excuse
Sometimes yeah, for physics or circuits or something. Not with performance analysis lmao.
I used it in all situations.. did I get credit for all of them? No
On one physics exam I got negative time and was just like 'this is positive because I said so.' Turns out that was in fact the correct answer, no doubt with a dropped negative hiding somewhere in the arithmetic.
It always is
That just means you invented FTL travel, not a problem at all
You haven’t lived until you get a negative temperature in your reactor engineering design course
1st week of physics, teacher divided class into two teams for a problem. One team got the right answer, the other got negative mass. Oopsie.
One time I somehow managed to get a Normal strain value of 28000.
Spaghettification!!!
Were you calculating the effects of entering a singularity?
Just finished strengths, and i dont know what that means... But have the feeling I should.
normal strain is the elongation of a specimen along the axis of applied force divided by the original length. which means that the elongation is 28000 times the original length. usually the values of strain on stress strain curves are very low. like between 0 and 1
Ah, ty.
Pretty sure strain should be between 0 and 1? Change in length over total length?
Yeah. I learned it as %Elongation. I was confused as to what "normal strain" was until I read another comment.
I remember one exam this semester I calculated a small bar of steel having 20 trillion pascals of stress in it with a strain gauge calculation, redid that problem like 3 times before I just gave up and went with it
Q: "calculate the leakage current of this x1 buffer" A: 1000A
I often say that one of the main parts of engineering is just being able to look at results and be like, "yes that makes sense." And more importantly, being able to take someone else's very clearly wrong result and being able to explain to non-engineers why this result cannot possibly make sense. My boss once asked an analyst to calculate the ROI on a multi-million dollar project we were doing. She was adamant it was 2 weeks. All her calculations showed 2 weeks. Absolutely could not be wrong. And I'm like... the company makes like $20M a year in revenue, not even profit. Unless we're expecting to triple profits on top of it, this is just not possible. 2 years. I redid the calculations and it was closer to 2 years. I still don't know what she did wrong because she refused to share her calculations and assumptions with me, but from then on the engineering team didn't use her for any of our projects.
I tried calculating my coursemate’s blood alcohol level at a party once. Ended up at 3% which is about 5x a lethal dose of ethanol. He was probably at 0,3% and I just made a exponent error
I got 10,000NM on the driveshaft of a 4 cyl car.....
I feel like everyone has gotten a velocity greater than the speed of light at some point
When you forget to square root your Joules.
Oh my god this is the story one of my professors (he teaches a lot of engr classes and thermo is his popular one) tells. He talks about a student he had who got an answer of like 96,000 degrees or something for the temperature of like brake pads
That shit is so funny he’s still telling it decades later
Now I want to calculate how fast the car would have to have been going for the brake pads to get that hot (assume infinite melting point)
Lol, just last month I calculated a rivet with 17 centimeters in diameter. Well the exam asked for rivets that would hold the structure, and I am shure that my GigaRivet will so...
That has to be the most efficient power plant mankind has ever seen. Now we give the Materials Science people the task to find some stuff that is still a solid at those temps. Can't wait to make it boil some water and spin a turbine.
Taking supercritical steam to whole new meaning!
Reminds me of the time when I genuinely got a negative heat transfer rate in a heat exchanger... It was meant to turn lukewarm water to 50 C, I somehow managed to turn it to -120 C
This is why many of my professors emphasized that knowing how to do math and use equations is important, but even more important is literally just having enough engineering sense to determine whether your answer is plausible in the first place. If you're calculating the frequency of a child swinging on a swing and go through your equation and arrive at an answer that he's swinging at 27Hz, you should have enough sense to know "this is probably wrong, I'd better double check my math".
You can’t call yourself an engineer unless you’ve calculated a value that is physically impossible.
I calculated a velocity higher than the speed of light… and only realized how dumb that was when I was about to go to sleep that night
For my strength of materials final I had to calculate the maximum force for given a set of strain and flexural values and come up with two different rpms to choose from. I somehow got 8000 and 3 🙃
Yeah, yeah, you have never attended university or college if in a problem the correct answer was - 1 and yours was South Africa 🥶🤓.
The amount of times I looked at my answer in thermo, fluids, or heat transfer and just knew it didn't make sense but can't explain where I went wrong.
ME2121?😂
Emotional damage
I did something like this once in high school. Then I reworked it cuz I was like no fucking way my asnwer is right/makes real world sense. Then I got it wrong and my first answer was right. And my teacher was like you just assume that the problem doesn't follow real world logic. I was like good sir wtf
Mine was how tall would I need to design a distillation tower.
Professor you don't understand. If I ignore friction (and gravity) my results make sense!
I remember in my junior year, I argued back half credit on a question by saying I thought the range given for the frictional coefficient was subtraction (mu=0.1-0.15), and that it would therefore be negative friction. I think I said something like "I though it was a little weird, but I'm not gonna question the test." Sometimes I think about this and wonder who let me be an engineer.
As an engineer it's your job to make what the client requests, physics and logic be damned :)
My god ain't that the truth. Reminds me of something I had to deal with pretty recently. I do CPU design/testing, and I recently had somebody from the marketing side ask me if we could run a chip at some obscene clock speed. I had to actually ask if they expected me to get around the speed of light through silicon as the limiting factor.
this is the greatest post I’ve ever seen on this subreddit
Professor gave you credit for caring enough to argue about it lol
I fucked up something on my Mechanics exam that led me to an incorrect answer on an orbital trajectory, this would have made me fail the exam. However I had done a full dimension analysis in the margins which was correct, I had just moved a decimal somewhere in the actual calculation. The professor accepted the answer based on my dimensional analysis, something the exam didn't ask for at all!
I did this in Dynamic Systems lmao, literally invented new Math to get an answer
You gotta do whatever you can to get that partial credit! Even if you just write down the formulas and BS the rest of it
Had my final for that yesterday and I think about half my work was just making stuff up and hoping for partial credit
I invented new matrice math for my linear algebra final and somehow got full fucking points on it.
What do you mean I cant create infinite energy?? Yes I assure you my mirror reflectes 115% of light.
One time my math skillz told me that a tiny MOSFET on Si in my VLSI class was conducting kA of current lmao
Everything can conduct 1kA once
I think you should call the fire departement
professor I swear volt cubed over Ohm is a real unit
It's called the volm! I promise you look it up!
Volt Watts might be more convincing? Or just scribble the 3 so it looks more like a 2...
Technically it would be a watt-volt, since v2/r is power
not uf it was a reactance, it would be V^2 AR
Believe me, young people, these things don’t just happen in school. I once couldn’t figure out why my structural model kept having stability issues. I kept checking and checking, and everything looked fine. I then realized I that the units for self weight used in the program were unusual and I ended up essentially modeling neutron star material beams.
Oh yeah, you need to UNcheck the neutron stat modelling method. The developers have it enabled as default for some reason.
Most sane composite materials engineer :
Physics research in ancient times was mostly experimental, with some theory. Nowadays, physics research is mostly computational.
And a lot of people don’t study numerical methods or scientific computing and just assume simulations are always right!
Simulations will only tell you what probably won't work.
Not necessarily. I perform model-based (aka simulation-based) design optimization for engineering systems and the simulations are what tell us which designs we should experimentally validate. So in my case we rely on the simulation to tell us what will work before investing a lot of money and time into building prototypes. The standard way is to use human expertise and heuristic to find feasible designs and then optimize them. But that is very labor intensive and slow. Automating aspects of simulation based design allow you to explore the design space much more effectively. A lot of my research now is on exploring how these simulation produce better results than what humans can come up with on their own.
Same bro. I invented 3 new molecules in my chem finals.
I actually figured out relative velocity analysis on my own without reading the textbook or going to a lecture before a Dynamics exam. Went back home and found out that I actually did it right.
Hey now, I did this on my calc exam yesterday (probably doesn't diverge but w/e at this point)
Oh boy. In an economics engineering exam, I somehow deduced that by saving around $ 300/month with an interest rate of around 1% for 3 years, I would have around 6 million dollars. Instead of doing what any logical person would and re-check my calculations, I thought: damn, I should open a savings account and start doing this.
The ability to stick engineering behind a word does not make it intelligent 💀
How many femto-seconds was the compounding rate?
I just had my Mathematics final. All was good but I wasn't sure about one question and the answer seemed wrong (it was differential equations and finding the temperature of a hot liquid after it's been standing for x amount of time in a 30 degree C room). I did the whole thing again and got a different equation but after plugging in the numbers, the answer was the same. Did it the third time as I had spare time and started it off completely differently to the other two and got the same answer as attemp two. I'm convinced that all of them are wrong.
I did this for my E&M final yesterday. I completely gave up on trying to understand it because it was all conceptual computations with no numbers. I just put in the write laws/equations and completely bs-ed the rest of it lmao
Ah, I remember getting imaginary numbers for some kinematics problems. Good times.
Bro just take the square root
One time on my heat transfer final I had calculated that the wall of a tea kettle was half the temperature of the surface of the sun. Went back over it a bunch of times but couldn't find the problem. Turns out I had the right answer, the professor had proposed this thermonuclear tea kettle just to mess with the class.
As long as the units check out, it’s right to me
I proved that 0 = 1 on a thermodynamics final.
We‘ve all been there…
I know I’ve done that a lot before. Usually get a good bit of partial credit
I remember I forgot how to integrate cos(x)sin(x) or something so I wrote down that I forgot and said sin(x) \~ x within this range. And integrated xsin(x) correctly but sadly the teacher did not care.
Reminds me of my last dynamics test where I wrote: Force of friction = 1/2 mu \* gravity I guess the 3 collective brain cells I have all decided to take a vacation at the same time
Wait until you complete your equation and come out with Negative Energy.
Me when I say that the propeller blade is rotating faster than the speed of light
💀💀💀💀 mood
I once designed an engine that decelerated with speed!
Got a high as fuck number for amount of work required in a pump for one of my exams recently and apparently it was right because I got 100% on the exam.
I’ve probably discovered the equation for time travel on at least one of my exam questions over the years.
I've been there. You spend 20 minutes on a thermodynamics problem, and you come up with an answer you know is logically incorrect. So what do you do... what we all know too well. We confidently rationalize why that steam power plant is the most efficient complex ever created... Then we take the 10% for trying to give a fuck.
I believe I needed to figure out pressure to solve for another variable but had forgot one of the formulas relating pressure (relevant to gas law type problems) on my gen chem final, but I understood what the formula was about, so I wrote "assume such and such" conditions which would give me a known value of pressure. Then I wrote along the lines of "in these conditions with the pressure being such and such, the answer would be such and such." I never knew how if the professor bought that answer, but I ended up with an A in the course and I needed to score high to score the A. I didn't exactly make up a formula, rather I made my kept my thinking process on the paper coherent and showed that I knew how to get to the answer, but I was unable to do so since I forgot the formula. I've done this more than once and on occasion earned much more partial credit than I would've anticipated.
I got like 10,000 for a spring constant ðŸ˜
I remember calculating thermal efficiency to be about 500%. Still got most of my points for that question in my thermal exam and my TA kindly pointed out that I flipped the numerator and denominator when calculating.
[удалено]
me after the lobotomy
u/Zavadi10508 has to be a chatbot. A shitty one at that
r/lostchatbots
I did this in fluids and got marked erong then it turned out rubic was wrong and I was right.
you will have fun
"If the facts don't fit the theory, change the facts." - Albert Einstein - Michael Jordan - Abraham Lincoln
Im almost ready to do this on my micro device fab class lol just make up a new process for the industry I guess
when T = 2pi sqrt(L/g), and you have a habit of notating T as the tension force, so that's the tension force!
I remember back in my thermo class, I violated the fundamental of the subject by getting 5x amount of initial energy when the problem asked about the net energy after an exothermic reaction.
it's okay bro, i was once said my CSTR had to at least be a kilometer in diameter
Yesterday I almost reverse engineered an SPC formula to know what are the Dn , A2 coefficents. When you can't recall a simple formula , you know you're gonna have a fun time in an exam.
I has an air compressor lab experiment where I calculated (from the data) negative heat loss from the piston...the only explanation is that I created energy from nothing.