Moving Right and Moving Left Post-Activity
1. In every case in this activity the graph of position vs. time was linear. What does
that tell you about the motion of the car?
Since the graph is linear the slope is constant. Therefore, the speed of
the car is constant.
2. The slopes of the position vs. time graphs in this activity differed in steepness and
in sign.
a. What does the steepness of a position vs. time graph tell you about the motion
of an object?
The steepness of a position vs. time graph represents how fast the object
is moving. The steeper the slope, the faster the motion.
b. What does the sign of the slope of a position vs. time graph (+ or -) tell you
about the motion of an object?
The sign of the slope of a position vs. time graph represents the direction
of motion. A positive slope indicates motion to the right while a negative
slope indicates motion to the left.
Moving Right and Moving Left Post-Activity
3. The y-intercepts of the position vs. time graphs in this activity were sometimes
different.
a. What does it tell you about the motion of the car when the y-intercept is above
the time axis (positive +)?
A positive (+) y-intercept means the car started to the right of 0.
b. What does it tell you about the motion of the car when the y-intercept is below
the time axis (negative -)?
A negative (-) y-intercept means the car started to the left of 0.
c. Overall, what does the y-intercept of a position vs. time graph tell you about the
motion of an object?
The y-intercept of a position vs. time graph represents the starting
position of the object
Moving Right and Moving Left Post-Activity
0 position
xcm
Remember that the slope of a position
vs. time graph isn’t only how fast the
object is moving, but the slope also
shows the direction of motion.
Position vs. Time
Velocity v  - The slope of a graph
of x vs. t
- The speed and the direction
with which an object moves
xo
t s 
Initial Position xo  - the y - intercept of a x vs. t graph
xcm 
Moving Right and Moving Left Post-Activity
Velocity v  - The slope of a graph
Position vs. Time
of x vs. t
- The speed and the direction
with which an object moves
xo
t s 
Vector – quantity having both a magnitude (size) and a direction.
*Vector quantities are denoted by placing an arrow over the variable.

x cm 
Moving Right and Moving Left Post-Activity

Velocity v  - The slope of a graph

of x vs. t
- The speed and the direction
with which an object moves
Position vs. Time

xo
t s 
Vector – quantity having both a magnitude (size) and a direction.
*Vector quantities are denoted by placing an arrow over the variable.
Scalar – quantity having only a magnitude (size).
i.e. mass, speed, distance

x cm 
Moving Right and Moving Left Post-Activity

Velocity v  - The slope of a graph

of x vs. t
- The speed and the direction
with which an object moves
Position vs. Time

xo
t s 
Final Position
y  mx  b
  
x  v t  xo
General Math Model for
one-dimensional,
constant velocity motion

x cm 
Moving Right and Moving Left Post-Activity

Velocity v  - The slope of a graph

of x vs. t
- The speed and the direction
with which an object moves
- The rate of change of position
(How quickly the position
changes)
Position vs. Time
t

x

xo
t s 
  
x  v t  xo
General Math Model for
one-dimensional,
constant velocity motion
Where

 x
v
t
  
x  x  xo

Displacement ( x ) - the change in position
Moving Right and Moving Left Post-Activity

Displaceme nt ( x ) - a vector quantity that refers to " how far out of place"
an object is; the object' s overall change in position
Distance ( d ) - a scalar quantity that refers to " how much ground an object
has covered" during its motion
A physics teacher walks 4 m East, 2 m South, 4 m West, and finally 2 m North.
4m
Distance = 12
? m
2m
2m
4m
Displacement = 0? m
“Walking the Graph”
Examples

x
Position vs. Time
t
A
0
A