Notes for Online Classes

Week of March 16th

Monday March 16
The objective today is to get a sense of how online Zoom would work. The questions I have are
(i) If I draw or write something on my screen then can all of you see it in real time?
(ii) Can each of you do the same?

(iii) How can we make the session interactive, for example, I can post a couple questions ahead of time which we can address collectively (I do not want this online interaction to be one way). I would like you to raise your hand if you have any question at all, or need clarification.

(iv) I would like that you take a few minutes of the class to write answers to one or more quesions, and we discuss the answers to those questions during this period.

The questions for today, I. Show that the magnitude of the change in potential energy in an elastically deforming body is always twie the change in the elastic energy.

II. What is the meaning of a negative sign for the potential energy and the positive or the negative sign for the elastic energy.

III. How is the above result instrumental in calculation the fracture condition for a penny shaped crack present within a body loaded with a uniaxial stress ="sigma".

Week of March 30th

Week of April 6th

Week of April 13th

Week of April 20th

Week of April 27th