- air resistance
- a frictional force that slows the motion of objects as they travel through the air; when solving basic physics problems, air resistance is assumed to be zero

- analytical method
- the method of determining the magnitude and direction of a resultant vector using the Pythagorean theorem and trigonometric identities

- classical relativity
- the study of relative velocities in situations where speeds are less than about 1% of the speed of light—that is, less than 3000 km/s

- commutative
- refers to the interchangeability of order in a function; vector addition is commutative because the order in which vectors are added together does not affect the final sum

- component (of a 2-d vector)
- a piece of a vector that points in either the vertical or the horizontal direction; every 2-d vector can be expressed as a sum of two vertical and horizontal vector components

- direction (of a vector)
- the orientation of a vector in space

- head (of a vector)
- the end point of a vector; the location of the tip of the vector’s arrowhead; also referred to as the “tip”

- head-to-tail method
- a method of adding vectors in which the tail of each vector is placed at the head of the previous vector

- kinematics
- the study of motion without regard to mass or force

- magnitude (of a vector)
- the length or size of a vector; magnitude is a scalar quantity

- motion
- displacement of an object as a function of time

- projectile
- an object that travels through the air and experiences only acceleration due to gravity

- projectile motion
- the motion of an object that is subject only to the acceleration of gravity

- range
- the maximum horizontal distance that a projectile travels

- relative velocity
- the velocity of an object as observed from a particular reference frame

- relativity
- the study of how different observers moving relative to each other measure the same phenomenon

- resultant
- the sum of two or more vectors

- resultant vector
- the vector sum of two or more vectors

- scalar
- a quantity with magnitude but no direction

- tail
- the start point of a vector; opposite to the head or tip of the arrow

- trajectory
- the path of a projectile through the air

- vector
- a quantity that has both magnitude and direction; an arrow used to represent quantities with both magnitude and direction

- vector addition
- the rules that apply to adding vectors together

- velocity
- speed in a given direction