Lecture 1: Classical Mechanics: Image Game

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  1. Image Questions
  2. Image Answers
  3. Videos



  1. Image Questions



      • Which quantity is a vector?




      • What is this?




      • Is the top object at rest?




      • two-body system   orbit animation  binary star orbit

        + marks the center of mass and it can't be accelerated without ___________?




      • What laws of nature are being illustrated?




      • The black curve shows a parabolic trajectory for ballistic flight in the absence of ____________ and the other curves show quasi-parabolic trajectories with ____________.




      • What principle is being illustrated in this somewhat busy gif?




    1. What is flowing through a complex system in this illustration?



  2. Image Answers








      • Caption: "Sundial in thyme garden at Minnesota Landscape Arboretum. Photographed June 17, 2007 at 12:21 solar time (13:21 Daylight Savings Time)." I don't think this is really an antique sundial from 1642.

        This is a horizontal sundial. Horizontal sundials are easy to read, but the markings cannot be evenly spaced in order to give the true solar time hours and the spacing is latitude dependent.

        There are all kinds of sundials and they are rather complicated things because of all the geometry of angles, lines, and planes involved.

        Credit: User:SEWilco.

        Permission: Use under GNU Free Documentation License.

        Image linked to Wikipedia.




      • Caption: Free body diagrams of objects: one on a horizontal plane; one one an inclined plane.

        The top object could be moving with constant velocity in the horizontal direction.

        Credit: User:Penubag.

        Permission: Public domain at least in USA.

        Image linked to Wikipedia.






      • Caption: "Trajectories of three objects thrown at the same angle (70 degrees). The black object doesn't experience any form of drag and moves along a parabola. The blue object experiences Stokes' drag, and the green object Newton drag".

        The curves with drag may not be for air or any other particular system.

        ANS: drag AKA air resistance when the drag is for air.

        Credit: User:AllenMcC. AKA Allen McCloud.

        Image linked to Wikipedia.

        Permission: Licensed under the Creative Commons Attribution ShareAlike 2.5.




      • Caption: "Elastic and Inelastic Collision. Example (m1 = 4kg, u1 = 5m/s, m2 = 4kg, u2=0m/s) of collision carts in perfectly inelastic collision showing the equations of momentum conserved and kinetic energy associated with some energy loss. This example (m1 = 4kg, u1 = 5m/s, m2 = 4kg, u2=0m/s) of collision carts in perfectly inelastic collision, notice the center of mass of the masses m1 and m2 is at the location of vcm = 2.5m/s always throughout the motion."

        ANS: Conservation of momentum in the absence of an external net force. The two carts are collectively one system and the collision forces are internal forces.

        Credit: User:Lookang.

        Image linked to Wikipedia.

        Permission: Licensed under the Creative Commons Attribution ShareAlike 2.5.




    1. Caption: "Basic overview of energy and human life."

      Immensely complex processes are going on in turning food energy (i.e., food chemical energy) into human chemical energy and then into human kinetic energy and then into waste heat (waste in the sense it is usually of no use to us) which ultimately flows out into space as the energy of infrared radiation.

      In space, the infrared radiation will mostly cool off and dilute forever in our current favored version of Big Bang cosmology---which may not be correct.

      But despite that complexity, we can crudely understand the processes in terms of energy flows and conservation of energy.

      I think my own favored definition of energy helps to energy:

        Energy is the conserved essence of structure and transformability.

      The definition takes some explication which we won't give here---but you probably get the drift anyway.

      Credit: Mikael Haeggstroem.

      Permission: Public domain at least in USA.

      Image linked to Wikipedia.



  3. Videos