Chapter 2 Representing Motion

model

a representation of an idea, event, structure, or object to help people better understand it

motion diagram

a series of images showing the positions of a moving object at equal time intervals

particle model

a simplified version of a motion diagram in which the object in motion is replaced by a series of single points

dimension

extension in a given direction; one dimension is along a straight line; three dimensions are height, width, and length

coordinate system

a system that defines the zero point of the variable you are studying and the direction in which the values of the variable increase

origin

the zero point
-point at which both variables have the value zero

position

the location of an object relative to an origin

distance

the length of how far an object is from the origin
-a scalar quantity that is the length, or size, of the displacement vector

magnitude

the size of a quantity

Vectors

quantities that have both magnitude and a direction
-vector quantities will be represented by boldface letters

Scalars

quantities that have only magnitude (do not include direction)
-numbers without any direction, such as distance, time, or temperature
-represented by regular letters

time interval

the difference between the initial and the final times
-formula t(f) - t(i)
-common symbol is (traingle)t, where the greek letter delta, is used to represent a change in quantity
-scalar

Displacement

the vector quantity that defines the distance and direction between two positions
-change in position
(triangle)x = x(f) - x(i)

resultant

a vector that represents the sum of two other vectors

intersection

a point where lines meet and cross

position-time graph

a graph with time data on the horizontal axis and position data on the vertical axis

instantaneous position

the position of an object at a particular instant

average velocity

ratio of the change in position to the time interval during which the change occurred

V ≡ changex/changet = x(f) - x(i)/ t(f)-t(i)

≡ means that the left hand side of the equation is defined by the right hand side

-vector quantity

average speed

the slope's absolute value

instantaneous velocity

the speed and direction of an object at a particular instant
-the term velocity is represented by the symbol v