Drag point A or B.[br]Vector u will be the vector connecting A & B.[br]It is made up of component in the x direction ->[br]and the y components ^[br][br]A good reference on introduction to vectors [br][url=https://nrich.maths.org/2390]An Introduction to Vectors (GCSE Stage: 4 and 5), Toni Beardon, June 2004,February 2011, NRICH Article[/url]