when you use these symbols | |, does that mean absolute value of the vector size (since it is same as absolute value symbols)? Or do they just have a different meaning, that we just write the same symbols. So |U| automatically implies just the magnitude of U? Also, what is a unit vector e used for? Why do we need to multiply a vector U by this unit vector? If the problem provides me w/ an arrow and vector U = 50 Newtons. Why do I need to multiply it by e? I dont gett it.