http://www.real-world-physics-problems.com/physics-of-skateboarding.html
http://www.ehow.com/how-does_4564503_a-skateboard-work.html
http://www.click2sciencepd.org/physics-behind-skateboarding-0
http://www.exploratorium.edu/skateboarding/trick03.html
http://www.ehow.com/how-does_4564503_a-skateboard-work.html
http://www.click2sciencepd.org/physics-behind-skateboarding-0
http://www.exploratorium.edu/skateboarding/trick03.html