Search results

  1. F

    Electric motor contest - suggestions?

    there is a contest to build an electric motor for which we can get some bonus points on the final in my E&M class. they give us a very limited kit and we can only use what comes in the kit which is a couple pieces of thick poster board, 6 feet of insulated wire, a couple paper clips, a couple...
  2. F

    Problems with file sharing programs

    That can't be it, none of my friends here have had any trouble.
  3. F

    Problems with file sharing programs

    I haven't been able to get any file sharing programs to work with my computers connection. I'm using a school connection - T1 I think. I've tried Limewire, Ares, and WinMX. I got WinMX to connect and search, but nothing would download - they all just said Waiting for network response and then...
  4. F

    Wave or Particle?

    Can you elaborate on this? I haven't yet studied quantum physics, but to my knowledge we don't really know for sure what light actually is, only that sometimes it behaves like particles and sometimes it behaves like waves.
  5. F

    The final explanation to why kinetic energy is proportional to velocity squared

    I admit I didn't read the whole thread cause I'm feeling like a lazy ass tonight, but I saw alot of math, and in physics I like to think about why things occur without using equations. Of course you need them to get exact answers in problems, but its nice to just think about the concept to see...
  6. F

    Why are orbits elliptical?

    This may be wrong, but here's how I imagine it: The sun provides a certain centripital force with its gravity, which changes depending on your distance. If a planet comes along and it is moving with a certain velocity and has a certain mass, you could do the math and figure out the radius of...
  7. F

    Sodium Hydroxide and Plastic

    I have some crystallized sodium hydroxide drain cleaner that I want to use on my bathroom sink drain, but I just put in a plastic drain and the trap is plastic as well. The clog is past the trap, somewhere deeper. So will the NaOH be alright with the plastic? Not sure exactly what kind of...
  8. F

    Stargazing A telescope orbiting an outer planet?

    The idea popped into my head today of building an extreme telescope (larger than hubble) to orbit an outer planet such as Jupiter etc.. I'm thinking that with it being past the asteroid belt, we would be able to see farther and clearer than with the hubble. Is this an accurate assumption? The...
  9. F

    Stargazing What am I doing wrong? - Telescope Trouble

    I took the barlow out and it works pretty good now. Not a perfect image, but it's cloudy tonight so it seems to be working good. Which eyepieces are for higher magnification - long or short focal length?
  10. F

    Stargazing What am I doing wrong? - Telescope Trouble

    yea there is a barlow x3 before the eyepiece. its a refractor telescope.
  11. F

    Stargazing What am I doing wrong? - Telescope Trouble

    I decided to dust off my old telescope to see what I could see. I was looking at the moon and messing around, but I could only get a sharp image with the eyepiece removed. Without the eyepiece, I can focus in a good image with my glasses on or off, but with it in it is only a blob of white...
  12. F

    Gravitational Potential Energy and force

    whozum, I see what you're saying now. James, I understand now. My physics teacher didn't do a great job of clarifying. Also, I misread some of the class notes about it. The first formula I gave is the correct formula for difference in GPE, \Delta U. The second one is for the specific...
  13. F

    Gravitational Potential Energy and force

    whozum, you can't set a = 0 because the this gives you an improper integral. This also implies that the two objects, if allowed to "fall" toward each other, could become infinitely close, which is impossible. To find the GPE of the object at some distance, you have have some reference point...
  14. F

    Gravitational Potential Energy and force

    The gravitational potential energy (U) of an object, from some reference point - such as the surface of the earth, is defined as the amount of work required to move the object from the reference point to its position. The force of gravity is given by: F = -\frac{GMm}{r^2} where r is...
  15. F

    Torque - In Depth

    I have a few years of physics experience, and as I was thinking about a few things the other day, something about the concept of torque seemed a little weird to me. Simple Forces are easy to understand - gravity pulls down on an object, the ground pushes back up with an equal and opposite...
  16. F

    Energy required to keep air in a plasma state

    What if the electrodes had a non conductive sheild? You have one set of electrodes to create a spark to ionize the air, and a second set with the insulating coating that dont create current but just create a static electric field. Would the insulated electrodes hold the ions and electrons apart?
  17. F

    Energy required to keep air in a plasma state

    Say that you are continuously creating plasma with some sort of sparking device. How strong of an electrical field is required to keep this air in its ionized state, compared to the field needed to ionize it initially?
  18. F

    Simple Harmonic Motion - Period of a Pendulum

    i see where i went wrong, whoever said torque is a fucntion of time, is right. well it depends on angle as well as time, but i assumed it depended on angle alone. however, since it is already moving faster towards the bottom of its fall, it experiences this torque over a shorter time interval...
  19. F

    Simple Harmonic Motion - Period of a Pendulum

    hmmm....i was looking through the books proof of the regular formula and where they assumed that sin (theta) = theta, i left it in and ended up with a pretty simple formula that should work for all angles: T=2*pi*(L*sin(theta)/g*theta)^(1/2) i put this into my excel table and compared it...
  20. F

    Simple Harmonic Motion - Period of a Pendulum

    the torque is really only dependent on the angle the pendulum is at (max when horizontal and zero when vertical). it does change with time but the change isnt caused by the time change. i computed the average by integrating torque as a function of theta from zero to the starting angle, and...
  21. F

    Simple Harmonic Motion - Period of a Pendulum

    what is flawed with my calculation of the average torque? I just have basic physics knowledge, and my highest math is calc2, so your eliptical integral went over my head, alot of the stuff in your first formula is unfamiliar to me - starting at the first subscript 2, im not sure what the rest...
  22. F

    Simple Harmonic Motion - Period of a Pendulum

    ok but it seems to me that my formula should still work even tho i did it a different way...
  23. F

    Simple Harmonic Motion - Period of a Pendulum

    im disregarding all friction or any other dampening force. even with a larger angle it would still oscillate with a constant period and amplitude etc. so it is still SHM, it just can be described by the common pendulum formula because the error would be to great. Since even at small angles, my...
  24. F

    Simple Harmonic Motion - Period of a Pendulum

    We are talking about SHO in physics and the forumula for period T of a pendulum was introduced - T=2*pi*(L/g)^.5 where L is the length of the pendulum arm/string and g is acceleration due to gravity. the instructor also said this was an approximation that was only accurate for small angles...
  25. F

    Forces on a Bike

    ok you know that centripital force is given by F=mv^2/r right? since the bike is travelling in a horizintal circle, the centripital force has to be a lateral force towards the center of the circle. the only lateral force between the tire and the road is friction. in the vertical direction you...
  26. F

    Gravity, Kepler's Laws

    anyone have a proof of the forumula v= (GM(2/r - 1/a))^.5 ?
  27. F

    Gravity, Kepler's Laws

    ok, there are 3 parts to the problem: 1) vp=? 2) va=? 3) rp/ra=? once you have vp, I could easily find the other 2. i was surfing around the internet and happened to find that vp=54200m/s, which i plugged in and it was correct. then i calculated that va=963m/s and that rp/ra=0.0178 which...
  28. F

    Gravity, Kepler's Laws

    ok using the formula v= (GM(2/ra - 1/a))^.5 i can find va if i calculate a, since i already know ra. I used kepler's law of periods to calculate a=2.68*10^12m I plugged that back into the formula along with ra to calculate va=752m/s , which the computer says is wrong do you guys get...
  29. F

    Gravity, Kepler's Laws

    Using conservation of angular momentum relative to the Sun, find the ratio of the comet's perihelion distance Rp to its aphelion distance Ra from the values of vp and va. since distance of closest approach - perihelion distance and the aphelion distance are given, you would just divide the...
  30. F

    Gravity, Kepler's Laws

    oh ok, but still, even if i know both distances, i dont see how i would solve for vp
Top