Recent content by oddjobmj

  1. O

    Need guidance on pneumatic motorcycle fuel system

    We are leaning towards not injecting on the intake stroke simply to save fuel. But if we did inject it would be low pressure then on the compression cycle it would be, well, compressed. My intuition suggested it would act similar to a spring and we would lose very little especially considering...
  2. O

    Need guidance on pneumatic motorcycle fuel system

    Good questions. Yes, a pneumatic motor is a motor driven by compressed air but we're using CO2 because it's easy to store in a liquid form at room temperature at relatively low pressures which is not the case with air. Liquid CO2 has a much higher density than air (a factor of ~1200 at 800...
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    Need guidance on pneumatic motorcycle fuel system

    Hello, I'm a physics student at Michigan State and I started an applied physics club. One of our first major projects is converting a 4-stroke combustion engine into a pneumatic engine to drive a motorcycle. We completed the prototype using a 4.5 hp tecumseh 139cc motor, a 5lb CO2 tank, some...
  4. O

    Einsteins field equations us what type of index notation?

    Ah, the way the metric tensor was explained to me was with a triangle that might be in curved space which you are trying to find the hypotenuse of where the following is the metric tensor: Which comes from:
  5. O

    Einsteins field equations us what type of index notation?

    Thank you! It's not even wrapped into the components in anyway that might not be immediately visible?
  6. O

    Einsteins field equations us what type of index notation?

    I know that the metric tensor itself utilizes Einstein summation notation but the field equations have a tensor form so the μ and ν symbols represent tensor information. I'm trying to wrap my head around how Einstein used summation notation to simplify the above field equations but it seems...
  7. O

    Potential inside grounded, conducting sphere with dipole at center.

    The dipole potential is a constant times ##P_1##. Is that what you mean?
  8. O

    Potential inside grounded, conducting sphere with dipole at center.

    Not sure how to say this accurately but I know they are orthonormal. Perhaps I could multiply by ##P_m## and the only terms that would matter are the ones where m=n. I've seen that done but why and when to do that is unclear. I am familiar with the form of Fourier series but not really seeing...
  9. O

    Potential inside grounded, conducting sphere with dipole at center.

    ##V(R,θ)=0= \frac{kqdcos\theta}{R^2} + \sum_{n=0}^\infty A_nR^nP_n(cos\theta)## So: ##-\frac{kqdcos\theta}{R^2} = \sum_{n=0}^\infty A_nR^nP_n(cos\theta)## If n=1 then you can divide out the ##cos\theta## but justifying this (i.e. not considering other n values) is what I am not sure of. Also...
  10. O

    Potential inside grounded, conducting sphere with dipole at center.

    I'm sorry for leaving that out. It was written down but I must have forgotten to type it out: V(r=R)=0
  11. O

    Potential inside grounded, conducting sphere with dipole at center.

    Homework Statement Suppose a grounded spherical conducting shell of radius R surrounds a pointlike dipole at the center with \vec{p}=p\vec{k} Find the potential V(r,\theta) for r <= R. Hint: Use spherical harmonics regular at r=0 to satisfy the boundary condition. Homework Equations General...
  12. O

    Potential due to two oppositely charged half spherical shells

    I am starting to agree with you. I guess the force acting on this particle in the z direction doesn't count as work because it is perpendicular to the direction of motion... this is fundamental but not intuitive in this case from my perspective. That is the only force in the case of a dipole...
  13. O

    Potential due to two oppositely charged half spherical shells

    Well, in this case the net charge is zero. The potential is not zero, though, if that's what you are hinting at. If a positive test charge is placed on the x-axis where x>R and we move this charge towards our origin the force on our test charge in the x direction would be 0 but the vertical...
  14. O

    Potential due to two oppositely charged half spherical shells

    Symmetric as you rotate about z and anti symmetric about the xy plane. I mean, I realize that the problem has symmetries. It is blatantly spelled out in the problem and I've noted them several times in my replies. I am asking explicitly about how those symmetries manifest themselves in my...
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    Potential due to two oppositely charged half spherical shells

    It's clearly symmetric about z and mirrored on the xy plane. Looking for symmetry is always my first approach in this class. I am clearly missing the connection between symmetry and its manifestation in an integral, however. This is conceptually difficult for me, sorry! edit: Are you on the...
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