Recent content by Edge Of Pain

  1. E

    I Confusion about Dirac Notation (interferometer)

    Hello everybody, Dirac notation uses "bras"( <a| ) and "kets"( |b> ), which are row vectors and column vectors respectively, but what would something like |a, b> mean? It makes no notational sense to me Context: A couple of photons going through beam splitters in an interferometer. One is...
  2. E

    Driven simple pendulum - system of first order ODEs

    Yes. Also I tried to solve this entirely in terms of theta and x, as I said I would above, but it was pointless since the only way to get Python to numerically solve this is to tell it that x is defined as omega * t, then give t values. So obviously it gave the same thing.
  3. E

    Driven simple pendulum - system of first order ODEs

    Yeah, my thinking is the same and I think I just need to leave it at that (besides, numerically solving that system results in a graph which looks sensible). But there is a reason why I need it in terms of x - a later part of the question is that it asks for a plot of theta against...
  4. E

    Driven simple pendulum - system of first order ODEs

    Homework Statement We have a driven pendulum described by the following differential equation: \frac{d^2\theta}{dt^2} = \frac{-g}{l}\sin(\theta) + C\cos(\theta)\sin(\Omega t) I need to turn this second order differential equation into a system of first order differential equations (then...
  5. E

    Determine the currents in this electrical network

    In that case, RHS of all the equations should be 0 except for loop 1 which should be 240V (potential difference). Is that correct?
  6. E

    Determine the currents in this electrical network

    Homework Statement This is quite an easy problem but I'm not sure if I set up my equations correctly, and I want confirmation. We are given the following circuit: And our task is to determine the loop currents i_{1}, i_{2}, i_{3}, i_{4} . Homework Equations Kirchhoff's first law: sum of...
  7. E

    Pumping Bicycle tire: Find volume, work done, temperature

    OK, so I should use a rearrangement of PV^{\gamma} = P_i V_i ^{\gamma} in part b)? If so that makes me happy because it fits with what I understand. But I got gamma as 7/5 rather than 7/4 because diatomic at room temperature => f = 5. I will now find the work done using the right equation for...
  8. E

    Pumping Bicycle tire: Find volume, work done, temperature

    I'm just going through this textbook "Introduction to Thermal Physics" by Daniel Schroeder and I've not come across compression ratios or diesel engines yet. Also, no heating actually happened. Work was done, increasing the temperature, but no "heat" was added or removed.
  9. E

    Pumping Bicycle tire: Find volume, work done, temperature

    I'm sorry but I'm not sure how this relates to the problem unless I'm missing something.
  10. E

    Pumping Bicycle tire: Find volume, work done, temperature

    Homework Statement Daniel Schroeder, introduction to thermal physics problem 1.36 (page 26): "In the course of pumping up a bicycle tire, a liter of air at atmospheric pressure is compressed adiabatically to a pressure of 7 atm. (Air is mostly diatomic nitrogen and oxygen.) a) What is the...
  11. E

    Solving differential equation using Laplace Transform

    Homework Statement solve the following differential equation using Laplace transforms: y'' + 4y' + 4y = t^2 e^{-2t}, y_0 = 0, y'_0 = 0 y_0 and y'_0 are initial conditions. Homework Equations Using L to represent the Laplace transform, we have that L(y) = Y L(y') = pY - y_0 L(y'') =...
  12. E

    Focal length of converging meniscus lens filled with a liquid

    Thanks! I was thinking about this question for several days now :) I already thanked one of your posts in this thread so it won't allow me to thank you again.
  13. E

    Focal length of converging meniscus lens filled with a liquid

    OK. For the focal length of the liquid lens surrounded by air we have 1/f_2 = (n-1)(1/R_1 - 1/R_2) . But in this case R1 is 9cm and R2 is infinity. So 1/f_2 = (1.46 - 1)(1/9 - 0) = 0.05111... ∴ f_2 ≈ 19.6cm . Now, we do the same thing for the glass lens and then find the effective focal...
  14. E

    Focal length of converging meniscus lens filled with a liquid

    OK, I've done it once more and got a different answer. This time I'll show my working. Firstly, image will be formed on opposite side of outgoing like so we predict a negative effective focal length. Correct? Then, we apply the lensmaker's equation to both lenses. Call n_1 index of...
  15. E

    Focal length of converging meniscus lens filled with a liquid

    OK, thank you, but how does equation 2 apply to the liquid, since it has only 1 radius of curvature? EDIT: Wait, we can treat the edge of the liquid as a plane refracting surface so its other radius of curvature is equal to infinity and we have 1/R - 0. Correct? Using this I get around 17cm...
Back
Top