Recent content by yoshtov

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    Difficulty with relativistic units, eV/c^2

    I'm having some difficulty in working with units of mass at the quantum level. This difficulty most clearly manifests itself when I'm doing a Compton scattering problem. Recall that Compton scattering is given by \Delta \lambda =\frac{h}{m_{e}c}(1-cos(\theta )) and that the rest mass of an...
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    Question re: difference between Δx and dx

    Homework Equations dL = L0αdT ΔL = L0αΔT These two equations are both listed separately on my equation sheet. How are the dL and ΔL terms different?
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    Fluid pressure problem and units confusion

    Homework Statement Exercise Find the pressure at a depth of 10 m below the surface of a lake if the pressure at the surface is 1 atm. (Answer: With P0 = 1atm = 101kPa, ρ=103kg/m^{3}, and g= 9.81 N/kg, we have P = P0 + ρgh = 1.97 atm. The pressure at a depth of 10 m is nearly twice that at...
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    Reproduction of the phenomenon with sand

    You want the sand to behave as much like an ideal fluid as possible. Therefore, I would imagine you want the density of the sand to be as low as possible. You would also want the grains to be as small, and as uniform, as possible. You could accomplish both of these by running the sand through a...
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    A problem with time dilation help?

    Yes it can! :) This is one of the central points of relativity: simultaneity. At relativistic speeds, time moves differently. Time is not constant across the universe. Suppose you had two identical clocks. You place one on a spaceship and the other at rest next to you on earth. If the spaceship...
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    Resistance of a Wire Cube: Diagnol Faces

    I am assuming you mean the resistance at two diagonal vertices of the cube. Try plotting out all of the different paths that current can take from point A to point B, and then go from there. see if you can put it in the form of a circuit diagram. Drawing a picture of a cube (okay, drawing a...
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    What is Air Pressure? Understanding the Weight of the Atmosphere

    They can move in other directions, absolutely! In general, you don't need to worry about differences in air pressure with respect to height, except when you start considering near-airtight structures that cover a significant vertical part of the atmosphere. There is almost no difference in air...
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    Rate of change problem and solving equation

    but isn't this an exponential decay equation? the derivative w.r.t. time shouldn't yield a linear equation. Here's my thought: Start with the definition of exponential decay N(t)=N_{0}e^{-\lambda t} The goal at hand is to find the value of lambda. We know that, in one minute, we will have...
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    Why Does Current Direction Affect Voltage Sign in KVL Analysis?

    As I conceptualize it, entering a voltage source from the positive terminal acts like a resistor. This can occur if you have several batteries wired in parallel, and there is enough EMF present to "force" current to go the other way through the voltage source. In any case, the voltage source...
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    Square coil rotated in a B field

    i spoke with my engineering professor, and he said that there is a significant difference between "flux through a loop of wire" and "flux through a coil." He also said that this is something physics teachers argue about. In short: \Phi _{loop}=B\times A\times cos(\theta ) and \Phi...
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    Square coil rotated in a B field

    Sadly, we all make stupid mistakes, and I am no exception. Recall that flux is \Phi =BAcos(\theta ) Remember that area is NOT 0.11 m^2, but rather, 0.0011 m^2, as there are (100^2) square-centimeters in a square-meter. Anyway, run with the "adjusted" area, and find that \Phi =1\times...
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    Square coil rotated in a B field

    (I). I got 17.5 Hz as well. (II). Since \epsilon =-N\frac{d\Phi}{dt} and \Phi =BA{cos\boldsymbol{\theta}}, and the derivative of that is \frac{d\Phi }{dt}=-BA{sin}\theta \frac{d\theta }{dt}, we can say that the highest EMF value will be present when dFlux/dt is highest, and THAT will be the...
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    Projectile Motion Calculations at t = 10 s

    You're almost correct for "C." You've got a solid start. 35sin(20.6) is its INITIAL vertical velocity. Once it begins traveling upwards, however, it begins to slow down. Use the equation v=at+v_{0}. Use 35sin(20.6) as your v0 value, and take into account the acceleration due to gravity. For f...
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    Electron-Proton Relative Speed: Solving for 0.9c and -0.0994c

    Question: Why did you leave "0.9c" as it was, but then expressed "c" later as 2.98*10^8 m/s? (This is where your problem resides.)
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    Properties of electric charges - insulators and conductors

    Question 1 is phrased very unusually, but I think I can formulate a response. I think that, because the proton in the conductor is much, much closer to the electron than the proton outside of the conductor, the proton right next to the electron will have the greater effect, and the electron will...
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