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,
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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.
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3 comments:
I wasn't sure how the kinematics worked on this one... I used Ydotdot=r*Thetadotdot, (kind of like a=r*alpha) with y measured mositively downwards in my FBD. I first don't know if/why this is the right equation, and if it is, how does the sign convention work for this one?
Yes, that is correct: y_dot_dot = r*theta_dot_dot (with y measured positively down and theta measured positively CCW)
The way to work this is to write out the kinematics equation between the center of the drum and the point where the cable comes off the drum on the left side. Both the magnitude and sign come directly from these kinematics.
To check the sign, a positive movement of the block (down) corresponds to a positive rotation of the drum (CCW).
Does that help?
yes, that clears things up. thanks!
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