AP Physics - Chapter 1

motion

change of an object’s position/orientation with time

trajectory

the path along which an object moves. can be curved or straight.

motion diagram

image showing an object’s positions at several equally spaced instants of time.

operational definitions

concepts are defined in terms of a particular operation.

particle

object that can be represented as a mass at a single point in space

model

simplification of reality, allows us to focus on more important aspects of a phenomenon.

particle model

simplification in which we treat a moving object as if all of its mass were concentrated at a single point

position

your location at a particular instant in time

origin

fixed reference point from which all distances are measured

coordinate system

an origin and an axis marked in both the positive and negative directions

coordinate

the symbol that represents a position along an axis

displacement

a change of position. can be positive or negative because it is a signed quantity. moving closer to the origin = -displacement

time intervals

changes in time

uniform motion

motion at a constant speed

velocity formula

(displacement)/(time interval)

speed formula

(distance traveled in time interval)/(time interval)

significant figures

digits that are reliably known

SI units

metric units; system used by scientists

conversion factor

a ratio of values equal to 1

order-of-magnitude estimate

one-sig fig estimate. indicated by “~”

scalar quantity

a physical quantity described by a single number with a unit. can be positive, negative, or zero.

vector quantity

quantity with both a size and a direction.

magnitude

size or length of a vector. can be positive or zero, but not negative.

displacement vector

displacement can be represented by this.

velocity vector

how we represent the velocity of an object. arrow above letter that points in the direction of the object’s motion.