Recent content by danyull

  1. danyull

    Internal Energy of a Mole of Particles each with 3 Energy Levels

    Ah I remember this now! This also reminds me that I should study up on distinguishable and indistinguishable particles too. Thanks a bunch!
  2. danyull

    Rotating an ellipse to create a spheroid?

    Let's say your ellipse has axes of length ##A## and ##B##, and center ##(h,k)##, and is rotated by angle ##\theta##. This is represented by the equation $$\frac{((x-h)\cos(\theta)+(y-k)\sin(\theta))^2}{A^2}+ \frac{((x-h)\sin(\theta)-(y-k)\cos(\theta))^2}{B^2} =1.$$ If ##A>B## then I suspect the...
  3. danyull

    Internal Energy of a Mole of Particles each with 3 Energy Levels

    Hello, I'm doing some refreshers before going back to school. Stat mech is my shakiest and I'd appreciate some help on this problem. I know that for a single particle, the partition function will be $$Z = 1 + 2e^{-\beta\Delta} + 2e^{-4\beta\Delta}$$ and so its internal energy is $$\frac{1}{Z}...
  4. danyull

    Efficient Heat Engine and Final Temperature Calculation

    Homework Statement Two identical bodies of constant heat capacity ##C_p## at temperatures ##T_1## and ##T_2## respectively are used as reservoirs for a heat engine. If the bodies remain at constant pressure, show that the amount of work obtainable is ##W = C_p (T_1 + T_2 − 2T_f)##, where...
  5. danyull

    Average Energy for n-State Systems?

    Homework Statement Find the average energy ##\langle E \rangle## for (a) an n-state system in which a given state can have energy 0, ε, 2ε, 3ε... nε. (b) a harmonic oscillator, in which a state can have energy 0, ε, 2ε, 3ε... (i.e. with no upper limit). Homework Equations Definition of...
  6. danyull

    Ball thrown up a π/6 inclined plane: time in air and launch angle for normal impact

    Oops, yeah I realized that wouldn't work after trying it. Do you think I could set ##\vec {\mathbf v}' \cdot \hat {\mathbf x}' = 0## instead? Evaluating the velocity at the time I solved for, the vector points "down" in the coordinate system, which is perpendicular to the coordinate's unit...
  7. danyull

    Ball thrown up a π/6 inclined plane: time in air and launch angle for normal impact

    Ah, right I did. Thank you! I believe I have the second part too now. I'll just set ##\vec {\mathbf r}' \cdot \hat {\mathbf y} = 0## because the dot product is zero when the vectors are orthogonal. The x-component drops out, and the position ##y'## will be from the equation I just used...
  8. danyull

    Ball thrown up a π/6 inclined plane: time in air and launch angle for normal impact

    Thanks for your input! My professor wants us to practice rotated reference frames using matrix transformations, hence this homework problem. I think I figured out part (a). I just used the equation ##y' = v_{0,y}' t + \frac 1 2 a_y' t^2## and set it equal to 0, then solve for ##t##. I'm still...
  9. danyull

    Physics and math major interested in languages

    Thanks for the warm welcome! and for the compliment. I have a lot of friends from mixed backgrounds.
  10. danyull

    Ball thrown up a π/6 inclined plane: time in air and launch angle for normal impact

    Homework Statement A ball is thrown with initial speed v0 up an inclined plane. The inclined plane makes an angle of π/6 above the horizontal line and the ball is launched at an angle θ above the inclined plane. No air resistance in this problem. (a) How long does the ball stay in the air? (b)...
  11. danyull

    Physics and math major interested in languages

    Hello! I'm a physics and mathematics major hoping to go into theoretical physics. Besides physics and math, I like languages and I've taught myself Spanish, Japanese, and some German and Chinese. I also like playing piano, dancing, cooking, and watching nice TV shows. It's nice to meet you~