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.


The following is a reverse chronological order listing of the posts for the course blog. To add a post, click here (when adding posts, be sure to add a "label" in the box at the lower right side of the post window). To add a comment to an existing post, click on the "Comments" link below the post.


____________________________________________________

Dec 2, 2008

Lecture Example P. 75

For the problem on page 75 in our lecture notes, what is the numerical value for delta s that is used when computing the work for the system? I think its either the ten inches the drum drops or its the amount of cord that gets wrapped around the drum as it drops. Thanks
Posted by at
Labels:

2 comments:

812rbruins said...

Shouldn't they be equal to eachother? The change in distance it rolls should also be the change in rope length.

December 2, 2008 at 2:44 PM
CMK said...

Note that the point of contact of the drum with the incline (call it C) is a no-slip point; therefore C is the IC for the drum. Since the point where the cord comes of the drum (call this point D) is twice as far from point C as is point O, D moves twice as fast as point O. Therefore, D moves twice as far as O over any given period of time.

Summary: If point O moves 10 inches down the incline, then the end of the cord moves 20 inches down the incline. The work done by P is NEGATIVE.

December 2, 2008 at 2:46 PM

Post a Comment

Subscribe to: Post Comments (Atom)