Bibliography
websites
http://aplusphysics.com/community/index.php?/blogs/entry/1275-the-physics-of-walking/
https://www.grc.nasa.gov/www/k-12/airplane/newton1.html
http://www.asawicki.info/Mirror/Car%20Physics%20for%20Games/Car%20Physics%20for%20Games.html
http://hyperphysics.phy-astr.gsu.edu/hbase/mlif.html
books
Physics for Scientist and Engineers: 4th Edition