Physics 1224
Spring 2006
Exam #2 - Part A
Name: ______________________________________________________
SS#: ______________________________________________________
I.
Multiple Choice: _________________________________(40 pts)
II.
Fill in the Blank: _________________________________(39 pts)
III.
Fill in the Table: _________________________________(22 pts)
IV.
Short Answer:
__________________________________(32 pts)
Total For Part A: ______________________________________(137 pts)
Total For Part B : ______________________________________(235 pts)
Total For Exam: _______________________________________
GRADE :______________________________________________
I.
Multiple Choice (4 pts each)
1.
The work done in moving an object between two points is path-independent.
The force causing this movement must be
2.
a)
zero.
b)
constant.
d)
inelastic.
e)
none of these
c)
conservative.
Each block in the figure below has a mass of 1.00 kg distributed uniformly
throughout the block. The location of the x-coordinate of the center of mass is
a)
x = 2.50 m.
b)
x = 1.50 m.
c)
x = 1.00 m.
d)
x = 0.500 m.
e)
none of these.
y (m)
3
2
1
1
2
3
4
x(m)
3.
4.
A correct expression for the moment of inertia of the uniform solid cylinder about
axis AA' is?
a)
MR 2
4
b)
MR 2
2
c)
MR 2
d)
3MR 2
2
e)
none of these.
A
R
A'
The energy diagram shown might represent the potential energy of a proton as a
function of the distance "r" from the center of the nucleus of an atom. At a
distance "A" from the center
U
A
r
a)
The proton is in unstable equilibrium and the net force on it is zero.
b)
The proton is in stable equilibrium and the net force on it is at a maximum.
c)
The proton is in stable equilibrium and the net force on it is zero.
d)
The proton is in unstable equilibrium and the net force on it is at a
maximum.
e)
None of the above.
5.
6.
A body moves with decreasing speed. Which of the following is true?
a)
The net work done on the body is positive, and the kinetic energy is
increasing.
b)
The net work done on the body is positive, and the kinetic energy is
decreasing.
c)
The net work done on the body is zero, and the kinetic energy is
decreasing.
d)
The net work done on the body is negative, and the kinetic energy is
increasing.
e)
The net work done on the body is negative, and the kinetic energy is
decreasing.
A particle is moving uniformly in a circle that has a radius of 50 cm. Its angular
velocity is 96 rad/s. The tangential speed of the particle is
a)
192 m/s
b)
96 m/s
d)
zero
e)
None of these
c)
48 m/s
7.
8.
Starting from rest, a disk rotates with constant angular acceleration. If it takes 10
revolutions to reach an angular velocity of , then how many additional
revolutions are required to reach an angular velocity of 2?
a)
10 rev
b)
20 rev
d)
40 rev
e)
50 rev
c)
30 rev
A 22.0 kg warhead experiences a force that varies in time as depicted in the
following graph. Determine the impulse delivered to the warhead.
F (N)
a)
2000 Ns
400
b)
80.0 Ns
c)
1000 Ns
d)
750 Ns
200
t (s)
2
e)
None of the above
4
6
9.
An asteroid initially traveling with a speed of Vo is deflected by the attractive
gravitational force of the sun as shown below. Which of the following statements
must be true?
Vo
Sun
10.
a)
The angular momentum of the asetroid is initially zero
b)
The angular momentum of the asetroid increases as the asteroid
approaches the sun.
c)
The angular momentum of the astroid is conserved
d)
both a) and b) are true.
e)
none of the above are true.
Four 50 kilogram masses are at the corners of a square with 20 cm sides. What is
the moment of inertia of this system about an axis perpendicular to the plane of
the square and passing through its center.
a)
1 kgm2
b)
4 kgm2
d)
8 kgm2
e)
None of these
c)
2 kgm2
II.
Fill in the Blank (3pts each blank)
1.
Write the SI unit for energy.
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2.
Write the definition of power.
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3.
Write the definition of angular acceleration.
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4.
Write the definition of angular momentum.
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5.
Write the Work-Energy Theorem.
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6.
Write Chasile's Theorem in either words or an equation.
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7.
Write the definition of angular velocity.
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8.
Write the definition of mechanical energy.
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9.
Write the definition of torque.
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10.
Write the definition of the center of mass.
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11.
Write the parallel axis theorem in words.
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12.
State the in words the condition for conservation of mechanical energy of a
system.
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13.
Write the equation that defines of potential energy
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III.
Complete the Table (2 pt each):
Below is a table relating linear and rotational variables and formulas. Fill in the
missing entrees.
Linear Variables
Rotational Variables



x
E
m
p
t
x = xo + vxot + (1/2)axt2
K = (1/2)mv2
L=I
IV.
Short Answer ( In Words Not Equation) : 4pts Each
A.
What is the condition required for the mechanical energy of a system to be
conserved?
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B.
What is the condition required for the linear momentum of a system to be
conserved?
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C.
What is the condition required for the angular momentum of a system to be
conserved?
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D.
Using the principles of physics covered in your textbook, explain how a cat
falling backwards out of a tree manages to land on its feet.
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E.
An electric grinding wheel coasts for a minute or more after the power is turned
off, but an electric drill coasts for only a few seconds. Why the difference?
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F.
Suppose you catch a baseball and then someone invites you to catch a bowling
ball with either the same momentum or the same kinetic energy as the baseball.
Which would you choose? Explain.
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G.
In terms of the conservation laws, explain the difference between an elastic and
inelastic collision.
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H.
What are the conditions required for a rigid body to be in equilibrium?
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