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  1. J

    I Integrating FFT, python code

    Hi Mark, So the goal of this function is to accept the FFT of a discrete set of data points which represent an acceleration signal a(t) and find the position over time x(t). The input is fft(a(t))=a(w). I know that for ever harmonic in a(w), that the corresponding time domain signal is An(t) =...
  2. J

    I Integrating FFT, python code

    Hello, Thank you for taking time to read my post. I have a discrete set of data points that represent an acceleration signal. I want to take the integral of this set of points twice so as to get a function which represents the position over time. To accomplish this, I have taken the FFT of the...
  3. J

    I Extracting sinusoids from FFT

    will iFFT( FFT('O') * FFT(H) ), result in a backwards 9? I haven't ever find anything like that before. It seems interesting though.
  4. J

    I Extracting sinusoids from FFT

    Works perfectly! I can't believe that it was that straight forward. You have been very helpful. Here is my python code as a contribution to the community (this is obviously for a dummy signal): import numpy as n import matplotlib.pyplot as plt from scipy.fftpack import fft, ifft, fftfreq...
  5. J

    I Extracting sinusoids from FFT

    Hello, Thank you for taking time to read my post. Background: I have a accelerometer project that I am playing with that gives me the acceleration of the object. I can plot this data and it looks very nice. I want to integrate this to get the velocity and then integrate it again to get the...
  6. J

    Max force help

    Hello, I built a small potato cannon out of PVC pipe/steel. It's 15.5 cm long, and about 7.6 cm wide on the inside. It's made of 2 parts the barrel and combustion chamber (or as i refer to, "the death chamber"). the "death chamber" is cylinder about 7.6 cm long and 7.6 cm thick. and the...
  7. J

    Help with basic physics problem.

    MOST EXCELLENT! Thank you all so much for your time and patients:P
  8. J

    Help with basic physics problem.

    i thought i had to convert it to N/m much like you have to convert 57g to .057kg right?
  9. J

    Help with basic physics problem.

    ok so tell me if i do this right if i have a spring that has 1 lbs/in which equals 175.12 N/m and if I put that into this equation. (1/2)mv2 = (1/2)kx2 .5(.057)9.9^2=.5(175.12)x^2 then that x=.1786 which is roughly 7.03 inches. Is this all correct?
  10. J

    Help with basic physics problem.

    so if i have a 20 lbs/in spring that is one foot long i need to push it 1 foot back to get my 20 pounds of force?
  11. J

    Help with basic physics problem.

    what if i shaved my tennis balls (don't laugh) and lubed the pipe with a silicon based oil? (like they use for cleaning gun barrels, like waxing it) that would minimize friction wouldn't it? and yes it is getting just a bit. so pulling it back 12 inches gives a .285 lbs. So if a spring says...
  12. J

    Help with basic physics problem.

    http://www.boltscience.com/pages/convert.htm why is it when I try and input my work with this calculator (above) I get a huge error (like 300 lbs/in)? also would this be right then? (1/2)mv2 = (1/2)kx2 .5(.057)9.9^2 = 25x^2 x=.3342 so I would only need to pull it back .334 of a meter with a...
  13. J

    Help with basic physics problem.

    ok 50 N/m = 442.53 lbs/in (and vice versa) @cupid.callin so with (1/2)mv2 = (1/2)kx2 and mass=.057kg V=9.9 m/s k=50 I'd be write to do the equation and get (1/2).057*9.9^2 = (1/2)50x^2 x=.334 Would this be accurate? Thanks again (things are starting to get clearer)
  14. J

    Help with basic physics problem.

    ok the fact is I'm trying to build one of these at home and I want to find out what type of spring to buy. and my math didn't make any sense when it said 247 pound/in spring so i was hoping to find the right answer with you guys. But i guess to my dilemma no one can help me unless if I have...
  15. J

    Help with basic physics problem.

    So your saying 9.9 m/sec is wrong to begin with? Just a reminder I'm a HS student and my teacher just got done teaching us basic 2-d kinematics and now is moving into springs and forces and half the equations that r being presented to me I never even seen before in my life. "Physicists seldom...
  16. J

    Help with basic physics problem.

    so i should have my work converted to lbs/ft? can i ask you just off the top of your head what would be a probable estimate of what lbs/ft spring i would need? ok so lets just say 20 lbs/in converted = 240 lbs/ft (1/2)mv2 = (1/2)kx2 .5(.057)9.9^2=240x^2 2.793/240=x so x=.011? however this...
  17. J

    Help with basic physics problem.

    This isn't like a normal home work problem. It's like one of those that your teacher gives at the end of the week that is super hard for some extra credit. All I was told was that "If someone has a spring cannon that could shoot 10 m at a 45 degree angle what type of spring would need to be in...
  18. J

    Einestein favourite physicist?

    omg! i totally get springs now! lol -sarcasm- js i like this forums sense of humor :)
  19. J

    Help with basic physics problem.

    so should Vi=9.9 then? (if sin(45) = 1) ok how could i do that then? Like what formula would I need to use? Could i use ma=-kx?
  20. J

    Einestein favourite physicist?

    i understand this. i didn't ask the original question. but still doesn't help me understand springs :(
  21. J

    Einestein favourite physicist?

    j/w why is it tht a 100 people will post abt a crazy topic but no one will help me with my homework :(
  22. J

    Einestein favourite physicist?

    to many smiles to be non-conspicuous....
  23. J

    Einestein favourite physicist?

    lonely people do lonely things...
  24. J

    Help with basic physics problem.

    1. Homework Statement If a tennis ball with a mass of 57 g is shot out of a spring cannon at a 45 degree angle and goes 10m find the answer to the following questions: What is the velocity. What spring constant must the cannon have. What would be the constant converted into lbs/in. 2...
  25. J

    Einestein favourite physicist?

    maybe it's not a question as to who was Einsteins favorite whatever, but why?
  26. J

    Einestein favourite physicist?

    now now lets be rational we want the truth! then again what is the truth? can we prove that anything is true?
  27. J

    Einestein favourite physicist?

    yes those rolling stones were quite the bomb of physics back then.
  28. J

    Help me with springs.

    Isn't the k measured in N/m though? So if a 20 pound/in spring would have 2.257 N/m. would this be the same as the k? k=2.257?
  29. J

    Einestein favourite physicist?

    w8 stien-I invented the g-4 bomb didn't he!? or did he cut down tht cherry tree?
  30. J

    Einestein favourite physicist?

    Idk, some dude that invented relativity or something? :P
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