Welcome to the website of ME 274 for the Fall 2008 semester. On this site you can view blog posts, add your own blog posts and add comments to existing posts. In addition to the blog are links to course material: course information, information on solution videos, exams, quizzes, homeworks and other course-related material. Direct links to the homework solution videos are also available on the left side of this page.


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Oct 6, 2008

Blog Challenge Question No. 1

In the solution provided for Quiz No. 6, there is a question posed related the minimum rotation rate for bar OA such that the particle does not slip on bar OA. In particular, it was noted that if mu_s > tan(theta) the solution provides an imaginary value for omega_min. It was asked what physical significance does an imaginary solution for omega_min have.

For this blog challenge question, provided a written answer to this question. Submit your answer by either a comment to this post or an email attachment of a scan of your handwritten answer that will be posted by your instructor.

This challenge question is worth 10 blog participation points.

In order to give everyone a chance to see this question, do not submit any responses prior to 5PM on Wednesday, October 8.



3 comments:

Sheng Yang said...

In this problem, the friction force F = mu*N = mu * W * cos(theta). The force opposing F is W * sin(theta). When mu > tan(theta), F will always be larger, meaning the block has acceleration up the bar. This contradicts the initial condition where the acceleration is toward O. Omega_min then does not exist.

Sheng Yang said...

An imaginary omega would allow an acceleration up the bar rather than down.

CMK said...

Good responses. There are no real values for omega that allow for the block to move inward. Therefore, if the block slips, it must slip outward.