Name____________________________
Lab Partner(s)_____________________
HOMEWORK: INTRODUCTION TO MOTION
Distance(Position)-Time Graphs
Answer the following questions in the spaces provided.
1. What do you do to create a horizon tal
line on a distance-time graph?
________________________________
Stand still.
________________________________
2. How do you walk to create a straig ht line
that slopes up?
Walk at a steady (constant) speed away from the
________________________________
D
i
s
t
D
i
s
t
Time
origin (detector).
________________________________
3. How do you walk to create a straig ht line
that slopes down?
Walk at a steady speed toward the origin.
________________________________
D
i
s
t
________________________________
4. How do you move so the graph goes up
steeply at first, and then continu es up
gradually?
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First walk quickly away from the origin,
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at a steady speed then walk away more
Time
Time
D
i
s
t
Time
slowly also at a steady speed.
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5. How do you walk to create a U-shap ed
graph?
________________________________
First walk toward the origin, speeding up then
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slowing down. Reverse direction, speed up
________________________________
then slow down and come to rest.
Tools for Scientific Thinking
Homework-Introduction to Motion
H-1
D
i
s
t
Time
Motion and Force 9/92
©1987-92 CSMT Tufts U.
Answer the following about two obj ects, A and B, whose motion produc ed
the following distance (position) -time graphs.
D
i
s
t
a) Which object is
B
moving faster--A or B?_____
6.
B
A
A
b) Which starts ahead? _____
Define what you mean by
"ahead."
A
_________________________
starts out further from the
than B and they are both _
origin
________________________
moving
away from the origin
_________________________
c) What does the intersection mea n?
Time
______________________
Objects A and B are at the
______________________
same position at the same time.
______________________
Object B passes object A.
D
i
s
t
A
7.
B
Time
a) Which object is
moving faster? ____
Both about same speed.
b) Which object has a negative
velocity according to the
convention we
have established? ____
B
8. a) Which object is
moving faster?
D
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s
t
B
A
_____
A
b) Which starts ahead?
_____
B
Explain what you
mean by"ahead."
Time
_______________________
They are both moving toward the
_______________________
origin, and B starts closer to the
_______________________
origin.
Tools for Scientific Thinking
Homework-Introduction to Motion
H-2
Motion and Force 9/92
©1987-92 CSMT Tufts U.
Sketch the distance (position)-time graph corresponding to each of the following descriptions of the motion of an
object.
9. The object moves with a steady (co nstant)
velocity away from the origin.
10. The object is standing still.
11. The object moves with a steady (co nstant)
velocity toward the origin for 5 s econds and
then stands still for 5 seconds.
12. The object moves with a steady vel ocity
away from the origin for 5 seconds , then
reverses direction and moves at th e same
speed toward the origin for 5 seco nds.
13.
The object moves away from the
origin, starting slowly and speeding
up.
D
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t
a
n
c 0
e
0
5
10
T i m e(sec)
D
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t
a
n
c 0
e
0
5
10
T i m e(sec)
D
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a
n
c 0
e
0
5
10
T i m e(sec)
D
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a
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c 0
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0
5
10
T i m e(sec)
D
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t
a
n
c 0
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0
5
10
T i m e(sec)
Note: These graphs are examples of correct graphs.
Tools for Scientific Thinking
Homework-Introduction to Motion
H-3
Motion and Force 9/92
©1987-92 CSMT Tufts U.
Velocity-Time Graphs
After studying the velocity-time graphs you have made, answer the following questions:
+
V
e 0
l
Time
-
1. How do you move to create a horizontal line in the positive part of a velocity-time
graph?
Move at a steady (constant)_velocity away from the origin.____________________
_________________________________________________________________
+
V
e 0
l
Time
-
2. How do you move to create a straight-line velocity-time graph that slopes up from
zero?
Move away from the origin speeding up at a steady rate.______________
________________________________________________________________
+
V
e 0
l
Time
-
3. How do you move to create a straight-line velocity-time graph that slopes down?
Move away from the origin slowing down at a steady rate.________________
________________________________________________________________
+
V
e 0
l
Time
-
4. How do you move to make a horizontal line in the negative part of a velocity-time
graph?
Move witht a steady (constant) velocity toward the origin.____________________
________________________________________________________________
Tools for Scientific Thinking
Homework-Introduction to Motion
H-4
Motion and Force 9/92
©1987-92 CSMT Tufts U.
5. The velocity-time graph of an object is shown below. Figure out the total distance traveled by the object. Show
your work.
Distance = ______8______ meters.
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2
4
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V
e
l +2 o
c
0
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0
t
y -2 m/s
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+4
(2 m/s)(4 sec) = 8 m
6
8
10
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T i m e (s e c)
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-4
6. Both of the velocity graphs below, 1 and 2, show the motion of two objects, A and B. Answer the following
questions separately for 1 and for 2. Explain your answers when necessary.
a) Is one faster than the other? If so, which one is faster? (A or B)
b) What does the intersection mean?
c) Can one tell which object is "ahead"? (define "ahead")
d) Does either object A or B turn around? Explain.
1
2
A
V
E
L
B
V
E
L
B
0
A
0
TIME
a)
A always moves faster.____________
b)
They are moving at the same speed at
c)
d)
TIME
a)
First A ,then B after the intersection.
b)
They are moving at the same speed
that moment in time.
at that moment in time.__________
______________________________
___________________________
Can't tell. Velocity graph does not show
c)
Can't tell. Velocity graph does not_
the starting positions. ______________
show the starting positions. _____
______________________________
started.
No Velocities do not change sign._____
Tools for Scientific Thinking
Homework-Introduction to Motion
d)
H-5
__________________
No Velocities do not change sign.
Motion and Force 9/92
©1987-92 CSMT Tufts U.
Sketch velocity-time the velocity -time graph corresponding to each of the following descriptions of the motion of an
object.
7. The object is moving away from
the origin at a steady (cons tant)
velocity.
+
V
e 0
l
10
20
Time(sec)
10
20
Time(sec)
10
20
Time(sec)
10
20
Time(sec)
-
8. The object is standing still.
+
V
e 0
l
-
9. The object moves toward the
origin at a steady (constant )
velocity for 10 seconds, a nd then
stands still for 10 seconds.
+
V
e 0
l
-
10. The object moves away from the
origin at a steady (constan t)
velocity for 10 seconds, re verses
direction and moves back to ward
the origin at the same spee d for
10 seconds.
Tools for Scientific Thinking
Homework-Introduction to Motion
+
V
e 0
l
-
H-6
Motion and Force 9/92
©1987-92 CSMT Tufts U.
11.
Draw the velocity graphs for an object whose motion produced the distance-time graphs shown below on the
left. Distance is in meters and velocity in meters per second. (That is, the velocity is the number of meters
the object would move in one second.)
Note: Unlike most real objects, you can assume these objects can change velocity so quickly
that it looks instantaneous with this time scale.
+2
V
e +1
l
o
0
c
i
t
-1
y
(m/s) -2
4
D
i 3
s
t 2
a
n
c 1
e
(m) 0
4
D
i 3
s
t 2
a
n
c 1
e
(m) 0
4
D
i 3
s
t 2
a
n
c 1
e
(m)0
0
0
0
Tools for Scientific Thinking
Homework-Introduction to Motion
1
1
1
2
3
Time (sec)
2
3
Time (sec)
2
3
Time (sec)
4
4
4
5
+2
V
e
+1
l
o
0
c
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(m/s) -2
5
V +2
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+1
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c
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(m/s) -2
5
H-7
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4
5
Time(sec)
1
2
3
4
5
Time(sec)
1
2
3
4
5
Time(sec)
Motion and Force 9/92
©1987-92 CSMT Tufts U.
12.
Draw careful graphs below of distance and velocity for a cart that starts at the origin and—
a. moves away from the origin at a slow and steady (constant) velocity for the first 5 seconds.
b. moves away at a medium-fast, steady (constant) velocity for the next 5 seconds.
c.
stands still for the next 5 seconds.
d. moves toward the origin at a slow and steady (constant) velocity for the next 5
seconds.
e. stands still for the last 5 seconds.
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V +1
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m/s
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D
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a
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c
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0
0
5
10
15
20
25
T i m e (sec)
Tools for Scientific Thinking
Homework-Introduction to Motion
H-8
Motion and Force 9/92
©1987-92 CSMT Tufts U.