https://youtu.be/5EsMmdaYClQ
https://youtu.be/5EsMmdaYClQ
http://www.physicsclassroom.com/Physics-Interactives/Work-and-Energy/Its-All-Uphill/Its-All-Uphill-Interactive
http://www.physicsclassroom.com/Physics-Interactives/Work-and-Energy/Its-All-Uphill/Its-All-Uphill-Notes
https://docs.google.com/document/d/1q0A7tBCG2GAPbP2WErbLa_N-OqUPoCVXf_-EQfojNrE/edit