PY 205 First Exam

Point Particle

an object whose size, shape, and internal structure are not important to us in the current context, and which we can consider to be located at a single point in space

Velocity

combination of both speed and direction (precise value at any instant)

A change of velocity (speed or direction or both) indicates…

avg vel =

the existence of an interaction

= delta r / delta t

Constant Velocity (uniform motion)

No change in speed or direction

Newton’s First Law of Motion

Every body persists in its state of rest or of moving with constant speed in a constant direction, except to the extent that it is compelled to change that state by forces acting on it.

Force

is the way in which the amount of interaction is quantified

Unit vector

every component is less than or equal to one

magnitude = 1

Each of the numbers in the triple is called a ___ of the vector

component

Vector

x y and z components, represents magnitude times direction (|r| * rhat (unit vector/direction))

Position

described by vector components

Displacement

1. draw r1 and rf tail to tail

2. draw delta r from head (arrow) of ri to head of rf

Vector subtraction

1. draw vectors tail to tail

2. if calculating “final minus initial” then it is drawn from the tip of the “initial” to the tip of the “final” vector

Vector addition

1. draw vectors tail to tip

2. sum is from tail of first vector to tip of second vector