Software 33-131 Fall 2001

 Software VPython website (How to get and install VPython, including updates) Playing with the momentum principle Illustrates the momentum principle (Newton's 2nd law). Click in right window, then drag force vector with mouse button up. Object in left window moves under the influence of this single force. Rotating vectors Four parts of program to illustrate rotating vectors: (1) A rotating position vector; for example, planet in circular orbit. (2) Also display momentum vector. (3) On right, display momentum vector with tail at center. (4) On right, display just the momentum vector. Click anywhere to advance from one part to the next. The intent is to help in seeing that the momentum in circular motion is itself a rotating vector, so that its rate of change is omega*p. Threebody orbits (a zip file to be unzipped) Choose an orbit situation. During an orbit, click to stop and choose another. Note that two of the situations differ only very slightly in the initial value of x. The intent of the program is to demonstrate the great complexity of motion with just 3 objects, despite simple rules (Newtonian mechanics), and the high sensitivity to initial conditions in such a system. Speed of sound in a metal Four parts of program to model propagation of sound through a metal: (1) Click an atom to displace it, then click repeatedly to see motion. (2) Same as (1), but also shows graph of displacements. (3) Click an atom to displace it, click anywhere when pulse reaches right end. (4) Same as (3), but lead atoms (Pb) instead of aluminum (Al). Move to next part or back by clicking an atom at the end of the chain. Atoms at the end of the chain are fixed in position. Moon voyage (for use with a worksheet for Prob. 4.2 on Thursday Sept. 27) The worksheet asks you to add energy calculations and graphs to this program. Motion in a potential well (1) Click and release mouse button. (2) Drag from left to right with button up to create a potential energy well. Click to end drawing of well. (3) Click to specify the energy level. Moving red indicator represents separation r. (4) Click to stop, click again to choose a different energy level. Baseball with air resistance First you see a 100 mph baseball in a vacuum. Then click to see it again in air, at sea level.. Cross product of two vectors in 3D Drag the vector with the mouse buttons up to see the cross product. Translational and rotational angular momentum Click to cycle through various combinations of translational and rotational angular momentm. Large vector represents translational angular momentum of "point particle" system. (1) No rotational angular momentum; barbell doesn't change orientation on pivot. (2) Barbell locked to rotating arm and rotates with it; small rotational angular momentum. (3) Barbell rotates more rapidly, large rotational angular momentum. (4) Like (1).. (5) Like (2). (6) Like (3), but rotational angular momentum in opposite direction. Gyroscope supported by spring Click on rotor to see angular momentum and impulse arrows. Click again on rotor to hide these arrows. Click anywhere else to pause, click to proceed. Gyroscope supported by pedestal Illustrates nutation (up and down motion) as well as precession. Uses "Lagrangian" mechanics for the computations. Problem 10.4 Heat capacity Plots experimental heat capacity data for aluminum and lead. gas.py Hard spheres collide elastically; speed distribution approaches Maxwell-Boltzmann distribution. Mean free path Version of gas.py with one particle marked so you can follow its motion. Click to start the motion. Mean free path here is determined mainly by container size rather than gas density. Carnot engine Click anywhere to step through the first four phases, after which it runs, picking up speed. Eventually, due to numerical integration errors, it no longer reaches the design temperatures and simply oscillates.