This the Homework2 from Luming Nie (ln781@nyu.edu) The original project is downloaded from https://github.com/samuraipapa/4phyiscsBodies For the first part, I added 6 more squares onto the original jointing with 5 more joints. For the second part, I added a snake consists of 7 squares, jointed with 'SKPhysicsJointLimit' and 'SKPhysicsJointSpring'.