Recent content by zerakith

  1. Z

    How Does Traveling at 0.9c Affect Communication Signal Frequencies?

    Thank you for the response, my understanding of the situation was that these were burst signals sent at set intervals apart. Now that i think about it this is most likely equivilant to considering points of constant phase, as in the Relativistic Doppler stuff. As for the category, I'm glad I...
  2. Z

    How Does Traveling at 0.9c Affect Communication Signal Frequencies?

    Homework Statement During a space flight an astronaut communicates with Earth by sending radio signals at regular intervals. If he travels out and back at a speed of 0.9c. What is the ratio of the frequencies of receipt by a receipt by a terrestrial observer on the outward and return...
  3. Z

    Calculating the Potential using Laplaces Equation

    Ah I understand my error now. Thankyou very much!
  4. Z

    Calculating the Potential using Laplaces Equation

    Am I right in saying that i could simply say D is 0 for physical reasons (i.e the one you described). Also I tried putting the limits as 0 and r if I apply those limits on the two integrations i get simply that: \Phi_\text{inside}=\frac{-\rho r^2}{6 \varepsilon_0} If I only apply it to the first...
  5. Z

    Calculating the Potential using Laplaces Equation

    1. The question asks to prove that for a sphere (radius R) of constant charge density, \rho, the potential inside the sphere is \Phi=\frac{\rho}{6\varepsilon_0}(3R^2-r^2) Homework Equations \nabla^2\Phi=0 \nabla^2\Phi=\frac{-\rho}{\varepsilon_0} The Attempt at a Solution This should...
  6. Z

    Calculating Fractional Change in Angular Velocity of a Spinning Cone of Sand

    I have now figure this out, the cone was vertical with the apex pointing downwards, hence it was simply matter of finding the new height of the cone, given that there was half the mass.
  7. Z

    Calculating Fractional Change in Angular Velocity of a Spinning Cone of Sand

    1. A light, hollow cone is filled with sand set spinning about a vertical axis through its apex on a frictionless bearing. Sand is allowed to drain slowly through a hole in the apex. Calculate the fractional change in angular velocity when the sand level has fallen to half its original value...
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