Name _______________________________________________________________________
Exam #1
Physics I
Fall 2007
Print your name on every page and circle section number below.
Section #
1
2
3
5
9
6
7
10
8
M/R 8-10 (Washington, DCC308)
M/R 10-12 (Yamaguchi, DCC308)
M/R 12-2 (Yamaguchi, DCC308)
M/R 2-4 (Eah, DCC318)
M/R 4-6 (Eah, DCC318)
T/F 10-12 (Malak, DCC324)
T/F 12-2 (Wetzel, DCC324)
T/F 12-2 (Adams, DCC308)
T/F 2-4 (Adams, DCC308)
Questions
Part A
Value
60
Part B
16
Part C
24
Total
100
Score
You may detach the formula sheet, but leave exam pages attached.
Cheating on this exam will result in an F in the course.
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Name _______________________________________________________________________
Part A – Multiple Choice (6 points each)
Circle the letter of the best answer.
1. The position of a particle moving along the axis depends on the time according to
an
equation = ¡ . In units of length, L, and time, T, the dimensions of the quantities
and are respectively:
A. L2/T, L3/T2
B. L/T2, L2/T
C. L/T, L/T2
D. L3/T, T2/L
E. none of these
2. The coordinate of a particle is given by () = 16¡ 30, where the time is in
seconds and the position  is in meters.
At what time is the particle momentarily at rest?
A. 075 s
B. 13 s
C. 53 s
D. 73 s
E. 93 s
3. If A  (6m)iˆ  (8m) ˆj then 4 A has magnitude:
A. 10 m
B. 20 m
C. 30 m
D. 40 m
E. 50 m
2
Name _______________________________________________________________________
4. A plane traveling north at 200ms turns and then travels south at 200ms. The change
in its
velocity is:
A. zero
B. 200 ms north
C. 200 ms south
D. 400 ms north
E. 400 ms south
5. A ball is thrown horizontally from the top of a 20-m high building. It strikes the ground at
an angle of 45 degrees. With what speed was it thrown (Assume negligible air resistance,
as usual.)?
A. 14 ms
B. 20 ms
C. 28 ms
D. 32 ms
E. 40 ms
6. The unit of force called the Newton is:
A. 98kg ¢ ms2
B. 1 kg ¢ ms2
C. de¯ned by means of Newton's third law
D. 1 kg of mass
E. 1 kg of force
7. When a certain force is applied to a one kilogram ball its acceleration is 50 ms2. When
the same force is applied to a second object its acceleration is one-¯fth as much. The mass
of
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Name _______________________________________________________________________
the second object is:
A. 02 kg
B. 05 kg
C. 10 kg
D. 50 kg
E. 10 kg
8. A 25-kg crate is pushed across a frictionless horizontal °oor with a force of 20 N,
directed 20 degrees below the horizontal. The acceleration of the crate will have magnitude:
A. 027 ms2
B. 075 ms2
C. 080 ms2
D. 170 ms2
E. 470 ms2
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Name _______________________________________________________________________
9. Which one of the following statements is true?
A. the center of mass of an object must lie within the object
B. all the mass of an object is actually concentrated at its center of mass
C. the center of mass of an object cannot move if there is zero net force on the object
D. the center of mass of a cylinder must lie on its axis
E. none of the above
10. A 10-kg ball moving at 20 ms perpendicular to a wall rebounds from the wall at 15
ms.
The change in the momentum of the ball is:
A. zero
B. 05 N¢s away from wall
C. 05 N¢s toward wall
D. 35 N¢s away from wall
E. 35 N¢s toward wall
Part B – Graphing (16 points)
The graph of x versus t shown is for a particle in straight line motion. In the table provided,
indicate whether the velocity, v, and the acceleration, a, are positive (+), negative (–), or zero
(0), in each of the intervals, AB, BC, CD, and DE.
AB
v
a
5
BC
CD
DE
Name _______________________________________________________________________
Part C – Numerical Problem (24 points)
A 20.0 g bullet is fired horizontally at two blocks at rest on a frictionless table. The bullet passes through
block 1 (mass 1.26 kg) and embeds itself in block 2 (mass 0.4 kg). The blocks end up with speeds v1 =
0.640 m/s and v2 = 1.32 m/s. The blocks are deformed but their masses remain constant. Show your work
below each question.
a) (12 points) Find the speed of the bullet as it leaves block 1.
Answer: ________________
b) (12 points) Find the speed of the bullet as it enters block 1.
Answer:_________________
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Name _______________________________________________________________________
Formula Sheet for Homework and Exams – Page 1 of 2


U    Fcons  dx
1.
v f  v 0  a t f  t 0 
23.
2.
x f  x 0  v 0 ( t f  t 0 )  12 a ( t f  t 0 ) 2
24.
U g  m g (y  y 0 )
3.
x f  x 0  12 ( v 0  v f )( t f  t 0 )
25.
U s  12 k ( x  x 0 ) 2
4.
x f  x0  v f (t f  t0 )  12 a(t f  t0 )2
26.
27.
28.
 K   U  Wnoncons
s  r
v tangential   r
29.
a tangential   r
6.
v f  v 02  2ax f  x 0 
 

 F  Fnet  m a
7.
T
8.
a centripetal 
5.
9.
10.
11.
12.
13.
14.
15.
16.
17.
18.
19.
20.
2
2r
v
v2
 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
38.
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
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.
7
v 2,f 
2 m1
m  m1
v1,i  2
v 2 ,i
m1  m 2
m1  m 2

Formula Sheet for Homework and Exams – Page 2 of 2
46a.
46b.
47a.
47b.
48a.
48b.
49.

m m
| F | G 1 2 2
r

m m
F  G 1 2 2 r̂
r

1 | q1 || q 2 |
| F |
4  0
r2

1 q1 q 2
F
(r̂ )
4  0 r 2

1 | qi |
| Ei |
4   0 ri 2

1 qi
E
(r̂i )
4   0 ri 2


F  qE
50.
51.
52.
1 qi
4   0 ri
U  qV
 
V    E  dx
V
V
x
V
53y. E y  
y
V
53z. E z  
z

 
54. F  q v  B
mv
55. r 
qB
53x. E x  
Useful Constants
(You can use the approximate values on exams.)
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
8