Torque Resource:
http://www.physics.uoguelph.ca/tutorials/torque/Q.torque.intro.html
This resource explains the relation between lever arm and force to create torque. It gives an example of torque when it explains how torque is involved when opening doors. It also tells us that in order for an object to rotate, the force must be perpendicular to the lever arm.
Center of Mass Resource:
http://www.youtube.com/watch?v=0-h1GUTKvCI#t=53
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Hewitt-drew-it gives us an example of a dog on a plank hanging off of a cliff. He asks us how far the plank (and the dog) can hang off of the cliff, before falling over. He gives an equation to calculate this, and explains that the dog would fall if the plank overhung past the center of gravity of the plank and the dog. He gives us the same question with a girl rather, than a dog, on the plank, showing that the center of gravity will be closer to the girl because of her greater weight.
He leaves us with a question: Two meter sticks are attached to create a ninety degree angle. Where should you place you finger on the sticks to balance them?
I really liked your first post, mostly because it talked a bit about something called a pivot point, which helped me visualize why things fall. Your next two resources were good mostly due to the large amount of math in them. I liked that because I really have trouble figuring out math problems and they were a good preview. It was also cool how you found some videos by Mr. Hewitt
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