The distance between two points depends on the actual path you take. The displacement has the length and direction of the minimum straight-line between the two points. Polar coordinates have a straight-line length in a specified direction. Vectors can be added by arrowed lines in scale diagrams. The arrowed lines may be positioned sequentially or simultaneously.
Vector subtraction is done by adding the negative.
Vector components are vectors at right angles which add to give the original vector. Vectors may be added without scale diagrams by using components. The moment about the turning point is defined as the magnitude of the force, times, the perpendicular distance from the turning point to the line of action of the force. Mass measures the amount of matter that a body has, and weight is the gravitational force on a mass. Equilibrium means balanced forces, and centre of gravity is the point where all the gravitational force can be considered to act through.