Name _______________________________________________________________________
Exam #1
Physics I
Spring 2006
If you would like to get credit for having taken this exam, we need
your name (printed clearly) at the top and section number below.
Your name should be at the top of every page.
Section #
_____ 1
_____ 2
_____ 3
_____ 4
_____ 5
_____ 7
_____ 9
_____ 10
_____ 11
_____ 12
_____ 14
_____ 15
M/R 8-10 (Bedrosian)
M/R 10-12 (Hayes)
M/R 10-12 (Eah)
M/R 12-2 (Bedrosian)
M/R 2-4 (Hayes)
M/R 4-6 (Hayes)
T/F 10-12 (Wilke)
T/F 10-12 (Washington)
T/F 12-2 (Yamaguchi)
T/F 2-4 (Wetzel)
M/R 12-2 (Eah)
T/F 12-2 (Wilke)
Questions
Part A
Value
32
B-1
20
B-2
24
C-1
24
Total
100
Score
You may not unstaple this exam.
Only work written on the same page as the question will be graded.
Cheating on this exam will result in an F in the course.
1
Name _______________________________________________________________________
On this exam, please neglect any relativistic and/or quantum mechanical effects. If you don’t
know what those are, don’t worry, we are neglecting them! On all multiple-choice questions,
choose the best answer in the context of what we have learned in Physics I.
On graphing and numerical questions, show all work to receive credit.
Part A – Multiple Choice – 32 Points Total (8 at 4 Points Each)
Write your choice on the line to the left of the question number.
______ 1.
An object is thrown vertically upward into the air. Which of the following five
graphs represents the velocity (v) of the object as a function of the time (t)?
Neglect air resistance and take the positive direction as up.
______ 2.
The system shown below consists of a cart on a track with weight = 6 N, a string, a
pulley, and a hanging weight of 3 N. The hanging weight and cart are free to
accelerate. Assume friction and the masses of the string and pulley are all zero.
What is the magnitude of the
6N
acceleration of the cart if g is the
free-fall acceleration?
A)
B)
C)
D)
E)
______ 3.
A)
B)
C)
D)
E)
______ 4.
A)
B)
C)
D)
g / 6.
g / 4.
g / 3.
g / 2.
g.
3N
In the system in Question 2 above, what is the tension in the string?
1.5 N.
2 N.
3 N.
4 N.
4.5 N.
A cannon fires a cannon ball that explodes into two pieces in mid-air. The system
in this question is the cannon ball (or its pieces) after being fired but before the
pieces hit the ground. Neglecting air resistance, the momentum of the system is
conserved in the horizontal direction only.
conserved in the vertical direction only.
conserved in both the horizontal and vertical directions.
not conserved in either direction.
2
Name _______________________________________________________________________
Questions 5-8 refer to the graphs shown below. Two objects, A and B, moving in one dimension
are subjected to different non-constant net forces, Fa and Fb respectively. The graphs below
show the velocity of each object, va and vb respectively, from t = 0 to t = 6 seconds.
To answer questions 6-9, pick one correct answer for each question from these choices:
A)
Object A.
B)
Object B.
C)
The quantities are equal for both objects.
D)
Not enough information was given to decide.
va (m/s)
vb (m/s)
+4
+4
+2
+2
t (sec)
0
2
4
t (sec)
0
6
2
-2
4
6
-2
_______5.
Which object had the greatest total displacement from t = 0 to t = 6 seconds?
_______6.
Which object had the greatest magnitude of acceleration at any time from t = 0 to t
= 6 seconds?
_______7.
Which object had the greatest magnitude of force acting on it at any time from t =
0 to t = 6 seconds?
_______8.
Which object had the greatest magnitude of total impulse acting on it over the time
interval plotted?
3
Name _______________________________________________________________________
B-1 – Graphing – 20 Points
An object of unknown mass moves in one dimension subjected to the net force shown in the
graph below from t = 0 to t = 8 seconds. The object begins at rest. Graph the momentum of the
object as a function of time from t = 0 to t = 8 seconds.
Make sure your plots clearly show:
A. Any minimum or maximum points.
B. Whether the graph is curved or straight.
C. The values of momentum at t = 0, 2, 4, 6, and 8 seconds.
Note: You may not assume an arbitrary value for the object’s mass to do this problem.
Fnet (N)
2
1
0
-1
t (sec)
2
4
6
8
-2
p (kg m/s)
t (sec)
2
4
6
8
4
Name _______________________________________________________________________
B-2 – Graphing – 24 Points
A circus performer swinging on a rope lets go at the bottom of the arc. Just before he lets go, he
is moving at 9.8 m/s horizontally and 0.0 m/s vertically. He is 19.6 m vertical distance above
the surface of a tank of water, which has been placed a horizontal distance d meters ahead of
where he lets go of the rope. The distance d was adjusted so that the performer falls into the
center of the tank of water.
Use g = 9.8 m/s2 and neglect air resistance.
vi = 9.8 m/s
d=?
19.6 m
tank of water
You can use this page for scratch work. We will not grade this page.
See the next page for the graphs that you will be drawing.
5
Name _______________________________________________________________________
B-2 – Graphing – 24 Points (Continued)
Plot the velocity and displacement of the circus performer from t = 0 (the starting time) to t = 2
seconds. Assume the initial location of the performer is (0.0, 19.6) m. To save space, please plot
Vx and Vy on the same graph.
Make sure your plots clearly show:
A. Which curve is Vx and which is Vy
B. Whether the graphs are curved or straight.
C. The values of Vx, Vy, X, and Y at t = 0, 1, and 2 seconds.
Vx and Vy (m/s)
0
t (s)
1.0
2.0
X (m)
t (s)
0
1.0
2.0
Y (m)
t (s)
0
1.0
2.0
6
Name _______________________________________________________________________
Problem C-1 (24 Points)
A hockey puck (#1) sliding on frictionless at 10.00 m/s in the +X direction collides with a
second puck (#2) with the same mass initially at rest. After the collision, puck #1 is moving at
9.24 m/s in a direction 22.5° counter-clockwise from its original direction.
What is the velocity of puck #2 after the collision?
Y
Puck #1
9.24 m/s
22.5°
X
Puck #2
? m/s
Vx of Puck #2 = _________________________________________ m/s
Vy of Puck #2 = _________________________________________ m/s
7
Name _______________________________________________________________________
Formula Sheet for Homework and Exams – Page 1 of 2


U    Fcons  dx
1.
v  v 0  a t  t 0 
23.
2.
x  x 0  v 0 ( t  t 0 )  12 a ( t  t 0 ) 2
24.
U g  m g (y  y 0 )
3.
x  x 0  ( v0  v)( t  t 0 )
25.
U s  12 k ( x  x 0 ) 2
4.
x  x 0  v( t  t 0 )  12 a ( t  t 0 ) 2
26.
27.
28.
 K   U  Wnoncons
s  r
v tangential   r
29.
a tangential   r
1
2
6.
v  v  2a x  x 0 
 

F
  Fnet  m a
7.
T
5.
8.
9.
10.
11.
12.
13.
14.
15.
16.
17.
18.
19.
20.
2
2
0
2r
v
a centripetal 
2
v
 2 r
r
a radial  a centripetal


p  mv

 
dp
 F  Fnet  d t



J   Fnet dt   p


P   pi


dP
  Fext
dt
30.
  0  t  t 0 
31.
   0  0 ( t  t 0 )  12 ( t  t 0 ) 2
32.
   0  12 (0  )( t  t 0 )
33.
   0  ( t  t 0 )  12 ( t  t 0 ) 2
 2  02  2   0 
   
35a. a  b  a b sin( )
 
a  b  a y b z  a z b y î 
35b.
a z b x  a x b z  ĵ  a x b y  a y b x k̂
34.

36.
37.
M   mi
1
1
x cm   m i x i y cm   m i y i
M
M


P  M v cm
   
a  b  a b cos()  a x b x  a y b y  a z b z
 
W  Fd
 
W   F  dx
21.
K  12 m v 2  12 m (v x  v y )
22.
K f  K i  Wnet
2
38.
39.
40.
41.
42.
43.
2
I   m i ri


2
K rot  12 I  2
 
W     d
  
  r F

 dL

  I  d t
  
l  r p


L  l i


L  I
44x. m1 v1, x ,before  m 2 v 2, x ,before  m1 v1, x ,after  m 2 v 2, x ,after
44y. m1 v1, y ,before  m 2 v 2, y ,before  m1 v1, y ,after  m 2 v 2, y,after
44z. m1 v1,z ,before  m 2 v 2,z ,before  m1 v1,z ,after  m 2 v 2,z ,after
45a. v1,f 
m1  m 2
2 m2
v1,i 
v 2 ,i
m1  m 2
m1  m 2
45b.
8
v 2,f 
2 m1
m  m1
v1,i  2
v 2 ,i
m1  m 2
m1  m 2

Name _______________________________________________________________________
Formula Sheet for Homework and Exams – Page 2 of 2

m m
46a. | F |  G 1 2 2
r

m m
46b. F  G 1 2 2 r̂
r

1 | q1 || q 2 |
47a. | F | 
4  0
r2

1 q1 q 2
47b. F 
(r̂ )
4  0 r 2

1 | qi |
48a. | E i | 
4   0 ri 2

1 qi
(r̂i )
48b. E  
4   0 ri 2


49. F  q E
50.
51.
52.
1 qi
4   0 ri
U  qV
 
V    E  dx
V
V
x
V
53y. E y  
y

 
54. F  q v  B
mv
55. r 
qB
53x. E x  
Useful Constants
(You can use the approximate values on tests.)
Universal Gravitation Constant
G  6.67310 11 N m 2 kg 2  6.67 10 11
Electrostatic Force Constant
1
 8.987551788 10 9 N m 2 C  2  9.0 10 9
4  0
Magnetic Constant
 0  4  10 7 H m 1  1.26 10 6
Speed of Light in Vacuum
c  2.99792458 10 8 m s 1  3.010 8
Charge of a Proton
e  1.602176462 10 19 C  1.6 10 19
Electron-Volt Conversion Constant
1eV  1.602176462 10 19 J  1.6 10 19
Mass of a Proton
m p  1.6726215810 27 kg  1.67 10 27
Mass of an Electron
m e  9.10938188 10 31 kg  9.110 31
9