phys1441-spring08-040908-post

phys1441-spring08-040908-post - Wednesday, Apr. 9, 2008...

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Unformatted text preview: Wednesday, Apr. 9, 2008 PHYS 1441-002, Spring 2008 Dr. Jaehoon Yu 1 PHYS 1441 Section 002 Lecture #20 Wednesday, Apr. 9, 2008 Dr. Jae hoon Yu Fundamentals of Rotational Motion Equations of Rotational Kinematics Relationship Between Linear and Angular Quantities Rolling Motion Wednesday, Apr. 9, 2008 PHYS 1441-002, Spring 2008 Dr. Jaehoon Yu 2 Announcements 3 rd term exam Monday, Apr. 21, in class Covers: Ch. 6.7 what we complete next Wednesday, Apr. 16 This is the final term exam in the semester The worst of the three term exams will be dropped from the final grading Colloquium today at 4pm SH101 Wednesday, Apr. 9, 2008 PHYS 1441-002, Spring 2008 Dr. Jaehoon Yu 3 Colloquium Today Title: The Solar Chromosphere: Is it always hot, or mainly cold? How is it heated? Dr. Wolfgang Kalkofen Harvard-Smithsonian Center for Astrophysics The Sun belongs to a class of stars in which the energy generated in its interior is transported through the subsurface layers by convection. In the process, waves are emitted that heat the outer solar atmosphere. Are they mainly acoustic waves, internal gravity waves, or waves associated with magnetic fields? There is no agreement among students of this question. It comes as no surprise then that models of the structure of the solar chromosphere differ widely. In addition, the total radiative energy flux emitted from the chromosphere of the Sun appears to be atypical for its class. What is the problem? And conceivable solution? Numerical simulations of wave heating of the chromosphere as well as ground-based and space-based observations should answer the question. The usual criterion, agreement between observations of emergent radiation and model predictions, has failed to provide an answer. The question dates back to the middle of last century. Why has it not been answered? Or has it? Wednesday, Apr. 9, 2008 PHYS 1441-002, Spring 2008 Dr. Jaehoon Yu 4 In the simplest kind of rotation, points on a rigid object move on circular paths around an axis of rotation. Rotational Motion and Angular Displacement The angle swept out by a line passing through any point on the body and intersecting the axis of rotation perpendicularly is called the angular displacement. = o Its a vector!! So there must be directions How do we define directions? +:if counter-clockwise-:if clockwise The direction vector points gets determined based on the right-hand rule. These are just conventions!! Wednesday, Apr. 9, 2008 PHYS 1441-002, Spring 2008 Dr. Jaehoon Yu 5 (in radians) = For one full revolution: 2 r a d = = SI Unit of the Angular Displacement Arc length Radius = s r Since the circumference of a circle is 1 radian is 1 rad 360 1 2 rad = o 180 1 rad = o 57.3 D...
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This note was uploaded on 10/21/2009 for the course PHYS phys1441 taught by Professor Dr.jhaehoonyou during the Spring '08 term at UT Arlington.

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phys1441-spring08-040908-post - Wednesday, Apr. 9, 2008...

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