# Engineering Science 1022A/B/Y Lecture Notes - Lecture 3: Unit Vector, Statics, Parallelogram

## Document Summary

Scalar - +/- quantity that can completely specified by its magnitude (no direction: ex. Vector quantity that requires a both a magnitude and direction for its complete description: ex. Force, position, moment: shown graphically by an arrow. Force vector represent push or pull along the vector axis: magnitude characterized by some unit ex. N, cm etc: direction angle between reference axis and arrow"s line of action, sense (push/pull) indicated by arrow head, point of application. Moment vector represents rotation about the vector axis: clockwise or counter-clockwise. Position vector distance along the vector axis to a point relative to the origin. Displacement vectors relative distance along the vector axis between two points. For vector a with magnitude of a the unit vector is: u. Cartesian unit vectors x axis i **with hat y axis j z axis k. R = a + b = b + a. Triangle law add vectors tip to tail.