1. Frictional force that develops between two surfaces in contact that are not moving relative to each other. 2. Pulling forces whose direction and point of application would tend to lengthen or stretch an object along the dimension coinciding with the line of action of the force. 3. State of an object as a result of forces pulling on it and producing tensile stress; tensile stress is axial stress that tends to pull molecules apart and stretch the object. 4. Constant rate of change in velocity; constant, unchanging acceleration. 5. Mathematical representation of any quantity that is defined by its size or magnitude (a number) and its direction (its orientation); vector quantities may be represented graphically by arrows, with the length of the arrow scaled to represent the magnitude of the vector and the shaft and head of the arrow oriented to represent the direction and sense of the vector along that direction. 6. instantaneous velocityThe rate of displacement measured at an instant in time rather than over a duration of time; expressed as units of length per unit of time or as meters per second in SI; a vector quantity