Recent content by JoshuaR

  1. J

    Calculating the Force on a Sloped Wedge & Scale

    Let's say you put a block on a flat scale. It measures weight of mg. You exert force exactly parallel to the scale, does the reading increase? How about it you put a second bloc on top of the first? Now the scale reads (M+m)g. How about if you slide one block but not the other, using only a...
  2. J

    What is the initial velocity of a rock thrown off a 20-m high cliff?

    Don't think in equations, think in terms of the picture you see. You grabbed the range equation, but don't just try to plug things into it. The rock strikes the ground at 45 degrees. That means it's final velocity has x and y components that are related to each other how? You know x velocity...
  3. J

    General Conservation of Momentum Problem

    For part B: You know the meteor's initial KE. What is that of the earth's? You know mass of earth, and velocity of earth-meteor, so you should be able to find KE of earth. There you can find the fraction. An additional question: Does this answer make sense? If yes, why, if not, why? What type...
  4. J

    What Do the Units Seconds/Degrees Squared Represent in a Pendulum Lab?

    Where did you get these units? Is this a final answer of yours, a constant, or from something else?
  5. J

    Particle Accelerator: Ideas & Experiments Needed for University Project

    Do you know any relativity? What might be useful about a particle accelerator, in regards to things like time dilation, length contraction, and how might that be more useful than a normal lab setting? That's just one idea. Good luck.
  6. J

    What Is the Minimum Possible KE of an Electron Confined to Nuclear Dimensions?

    Right, borgwal, I think that was the problem. Thanks again!
  7. J

    What Is the Minimum Possible KE of an Electron Confined to Nuclear Dimensions?

    I see. It all makes so much more sense now, lol. Just take away that darn factor... New question on this. I figured I should use minimum uncertainty for \delta x since we were confining it to a box of size 5E-15m. Do you suppose my problem here was assuming the box was \delta x? After all...
  8. J

    What Is the Minimum Possible KE of an Electron Confined to Nuclear Dimensions?

    Gah! Where's the math mistake? -.511MeV + sqrt[.511^2 + (6.58E-22*3E8/(2*5E-15))^2)
  9. J

    What Is the Minimum Possible KE of an Electron Confined to Nuclear Dimensions?

    Mmkay, I think I've tried that. I have \delta p\delta x = \hbar/2. Thus, when I use the KE form from before: KE = sqrt[(mc^2)^2 + (\hbar c/\delta x*2)^2] - mc^2 I must be doing incorrect math... sigh.
  10. J

    Calculating the Force on a Sloped Wedge & Scale

    What have you tried thus far?
  11. J

    Calculating the Distance and Velocity of a Thrown Object Using Kinematics

    Not sure what your question is exactly. 75 feet? Doesn't your problem say 70m? BTW, have you learned energy yet? If so, try equating potential and kinetic energy to find some useful information. That will help you with some of the parts. For (c), total distance, if you know the other...
  12. J

    What Is the Minimum Possible KE of an Electron Confined to Nuclear Dimensions?

    That was indeed my guess on the second approach. If I take just that: KE = sqrt[(mc^2)^2 + (pc)^2] - mc^2 , I still don't get there. Using the formula p = h/\lambda If I do as I did on the "second approach" then setting energies equal, I also have trouble. I'm a bit puzzled because I am sure...
  13. J

    What Is the Minimum Possible KE of an Electron Confined to Nuclear Dimensions?

    Homework Statement Consider an electron confined in a region of nuclear dimensions (about 5fm). Find its minimum possible KE in MeV. Treat as one-dimensional. Use relativistic relation between E and p. Homework Equations KE = p2/(2a) = \hbar2/(2ma2) p = h/\lambda E = hf E2 = (mc2)2 +...
  14. J

    How Are Electrons Deflected in Thomson's Experiment With Only a Magnetic Field?

    Um, I don't know if it's terrible to reply to a thread from so long ago, but I ran into the exact same problem and a different derivation (incorrect). Idea as follows, in the distance through the magnetic field, l, the electron moves a height h=ltan\theta. This same distance can be related...
  15. J

    Solve Statics Question: Vertical Reactions at A,D,F

    Someone suggests that force P may be only applied to beam BEF, not on beam DCE. Would that make it work?
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