THE MOVING MAN
Purpose: Students will select the sign of the initial position, velocity, and acceleration to match graphs
of the moving man’s motion. Students will attempt to discover the connections between graphs.
1) Go to http://phet.colorado.edu/new/simulations/sims.php?sim=The_Moving_Man. Familiarize
yourself with the program, then answer the following questions.
On each question 2 through 5, I would like you to try predicting the shape of the graph and then
run the experiment and see if you were right:
4) What does constant acceleration look
like on a position vs. time graph?
Position
Position
2) What does constant velocity look like
on a position vs. time graph?
Time
Time
5) What does constant acceleration look
like on a velocity vs. time graph?
Velocity
Velocity
3) What does constant velocity look like
on a velocity vs. time graph?
Time
Time
6) Select initial values for position, velocity, and acceleration to match both of the following
position vs. time and velocity vs. time graphs. When you match the curves indicate whether
each variable’s initial condition was positive, negative, or zero.
0
0
Time
(0)
(0)
(0)
0
(+)
(+)
(+)
Velocity
Position
a. position:
(-)
velocity:
(-)
acceleration: (-)
0
0
Time
0
0
0
0
(0)
(0)
(0)
0
0
(+)
(+)
(+)
Velocity
Position
b. position:
(-)
velocity:
(-)
acceleration: (-)
0
Time
0
0
0
(0)
(0)
(0)
0
0
0
0
0
Time
(0)
(0)
(0)
Time
0
0
0
0
0
0
0
0
0
Velocity
Position
0
0
(+)
(+)
(+)
0
0
0
Time
d. position:
(-)
velocity:
(-)
acceleration: (-)
0
0
0
Time
(+)
(+)
(+)
Velocity
Position
c. position:
(-)
velocity:
(-)
acceleration: (-)
0
Time
7) Describe the motion when initial velocity and acceleration have the same sign. Does it matter
if both are positive or both are negative? Choose an initial position, also. Choose at least one
case (v and a both positive or negative). By drawing the 3 small sketches to the left (i.e. the
graphs or x(t), v(t), and a(t), predict the shapes of all three graphs in this simulation. Then run
the simulation to see if you were right. Draw the graphs given by the simulation on the right
hand side. You should have a total of 6 graphs, at least.
8) Describe the motion when initial velocity and acceleration have opposite signs. Does it matter
which is positive and which is negative? Choose an initial position. Choose at least one case for
v and a having different signs. By drawing the 3 small sketches to the left (i.e. the graphs or
x(t), v(t), and a(t), predict the shapes of all three graphs in this simulation. Then run the
simulation to see if you were right. Draw the graphs given by the simulation on the right hand
side.
9) Create a few more cases (random) and look at the graphs of x(t) and v(t). Do you notice
anything that may relate these two graphs? (hint: the easiest to see the connection between x(t)
and v(t) is by choosing positive and negative values for v initial and run each case looking at
v(t) and x(t) graphs). Write your conclusion below. It helps to keep a=0 first, but this is not a
necessary condition to discover the connection wanted.
10) Do the a similar case as for part 9) but this time pay close attention to v(t) and a(t). (hint: the
easiest to see the connection between a(t) and v(t) is by choosing positive and negative values
for a initial and run each case looking at v(t) and a(t) graphs). Can you see any connection
between these two graphs? Explain.