Bottle in a Bottle 2

  • heat entropy ideal gas
    • assignment Bottle in a Bottle

      assignment Homework

      Bottle in a Bottle
      irreversible helium internal energy work first law Energy and Entropy 2021 (2 years)

      The internal energy of helium gas at temperature \(T\) is to a very good approximation given by \begin{align} U &= \frac32 Nk_BT \end{align}

      Consider a very irreversible process in which a small bottle of helium is placed inside a large bottle, which otherwise contains vacuum. The inner bottle contains a slow leak, so that the helium leaks into the outer bottle. The inner bottle contains one tenth the volume of the outer bottle, which is insulated. What is the change in temperature when this process is complete? How much of the helium will remain in the small bottle?

    • assignment Directional Derivative

      assignment Homework

      Directional Derivative

      Gradient Sequence

      Static Fields 2023 (6 years)

      You are on a hike. The altitude nearby is described by the function \(f(x, y)= k x^{2}y\), where \(k=20 \mathrm{\frac{m}{km^3}}\) is a constant, \(x\) and \(y\) are east and north coordinates, respectively, with units of kilometers. You're standing at the spot \((3~\mathrm{km},2~\mathrm{km})\) and there is a cottage located at \((1~\mathrm{km}, 2~\mathrm{km})\). You drop your water bottle and the water spills out.

      1. Plot the function \(f(x, y)\) and also its level curves in your favorite plotting software. Include images of these graphs. Special note: If you use a computer program written by someone else, you must reference that appropriately.
      2. In which direction in space does the water flow?
      3. At the spot you're standing, what is the slope of the ground in the direction of the cottage?
      4. Does your result to part (c) make sense from the graph?

    • assignment Free Expansion

      assignment Homework

      Free Expansion
      Energy and Entropy 2021 (2 years)

      The internal energy is of any ideal gas can be written as \begin{align} U &= U(T,N) \end{align} meaning that the internal energy depends only on the number of particles and the temperature, but not the volume.*

      The ideal gas law \begin{align} pV &= Nk_BT \end{align} defines the relationship between \(p\), \(V\) and \(T\). You may take the number of molecules \(N\) to be constant. Consider the free adiabatic expansion of an ideal gas to twice its volume. “Free expansion” means that no work is done, but also that the process is also neither quasistatic nor reversible.
      1. What is the change in entropy of the gas? How do you know this?

      2. What is the change in temperature of the gas?

    • grading Free expansion

      grading Quiz

      60 min.

      Free expansion
      Energy and Entropy 2021 (2 years)

      adiabatic expansion entropy temperature ideal gas

      Students will determine the change in entropy (positive, negative, or none) for both the system and surroundings in three different cases. This is followed by an active whole-class discussion about where the entropy comes from during an irreversible process.
    • face Work, Heat, and cycles

      face Lecture

      120 min.

      Work, Heat, and cycles
      Thermal and Statistical Physics 2020

      work heat engines Carnot thermodynamics entropy

      These lecture notes covering week 8 of Thermal and Statistical Physics include a small group activity in which students derive the Carnot efficiency.
    • group Projectile with Linear Drag

      group Small Group Activity

      120 min.

      Projectile with Linear Drag
      Theoretical Mechanics (4 years)

      Projectile Motion Drag Forces Newton's 2nd Law Separable Differential Equations

      Students consider projectile motion of an object that experiences drag force that in linear with the velocity. Students consider the horizontal motion and the vertical motion separately. Students solve Newton's 2nd law as a differential equation.
    • group Changes in Internal Energy (Remote)

      group Small Group Activity

      30 min.

      Changes in Internal Energy (Remote)

      Thermo Internal Energy 1st Law of Thermodynamics

      Warm-Up

      Students consider the change in internal energy during three different processes involving a container of water vapor on a stove. Using the 1st Law of Thermodynamics, students reason about how the internal energy would change and then compare this prediction with data from NIST presented as a contour plot.
    • assignment Icecream Mass

      assignment Homework

      Icecream Mass
      Static Fields 2023 (6 years)

      Use integration to find the total mass of the icecream in a packed cone (both the cone and the hemisphere of icecream on top).

    • group Applying the equipartition theorem

      group Small Group Activity

      30 min.

      Applying the equipartition theorem
      Contemporary Challenges 2021 (4 years)

      equipartition theorem

      Students count the quadratic degrees of freedom of a few toy molecules to predict their internal energy at temperature \(T\).
    • assignment Center of Mass for Two Uncoupled Particles

      assignment Homework

      Center of Mass for Two Uncoupled Particles
      Central Forces 2023 (3 years)

      Consider two particles of equal mass \(m\). The forces on the particles are \(\vec F_1=0\) and \(\vec F_2=F_0\hat{x}\). If the particles are initially at rest at the origin, find the position, velocity, and acceleration of the center of mass as functions of time. Solve this problem in two ways, with or without theorems about the center of mass motion. Write a short description comparing the two solutions.

  • Energy and Entropy 2021 (2 years)

    Consider the bottle in a bottle problem in a previous problem set, summarized here.

    A small bottle of helium is placed inside a large bottle, which otherwise contains vacuum. The inner bottle contains a slow leak, so that the helium leaks into the outer bottle. The inner bottle contains one tenth the volume of the outer bottle, which is insulated.

    The volume of the small bottle is 0.001 m23 and the volume of the big bottle is 0.01 m3. The initial state of the gas in the small bottle was \(p=106\) Pa and its temperature \(T=300\) K. Approximate the helium gas as an ideal gas of equations of state \(pV=Nk_BT\) and \(U=\frac32 Nk_BT\).

    1. How many molecules of gas does the large bottle contain? What is the final temperature of the gas?

    2. Compute the integral \(\int \frac{{\mathit{\unicode{273}}} Q}{T}\) and the change of entropy \(\Delta S\) between the initial state (gas in the small bottle) and the final state (gas leaked in the big bottle).

    3. Discuss your results.