Sample Exam 1

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Physics 213 Fall 2003 Midterm Form D
 
1. In the hydraulic press shown, the small piston "a" has diameter 3.8 cm and the larger piston "A"
has diameter 53.0 cm. What force magnitude f on the small piston will balance a 2.0 x 104 N
force F on the larger piston?
A. 0.1 N
B. 2.0 x 104 N
C. 103 N
D. 2.8 x 105 N
E. 3.9 x 106 N
2. A 1024 Hz tuning fork is used to obtain a series of resonance levels in a gas column of variable
length, with one end closed and the other open. The length of the column changes by 20 cm from
resonance to resonance. From this data, the speed of sound in this gas is:
A. 20 m/s
B. 410 m/s
C. 102 m/s
D. 205 m/s
E. 51 m/s
3. What fraction of the volume of an ice cube floats above the surface in a glass of water? Take the
density of ice to be 917 kg/m3 and water to be 998 kg/m3.
A. 3%
B. 90%
C. 0.1%
D. 10%
E. 8%
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Physics 213 Fall 2003 Midterm Form D
 
4. An irregular 3kg lump of material is submerged in a fluid. The fluid that would have been in the
space now occupied by the lump has a mass of 2 kg. When the lump is released, it
A. moves upward with an acceleration g/3.
B. moves downward with an acceleration g.
C. remains in place.
D. moves upward with an acceleration g.
E. moves downward with an acceleration g/3.
5. Fresh water of density ρ = 1000 kg/m3 is behind a reservoir dam that is 15 m deep. A horizontal
pipe 4.0 cm in diameter passes through the dam 6.0 m below the water surface, as shown in the
figure. After a plug securing the pipe opening is removed, how much water flows out in 3 hours?
A. 588 m3
B. 233 m3
C. 147 m3
D. 39 m3
E. 49 m3
6. What is the approximate minimum area of the top surface of a rectangular slab of ice 0.3 m thick
floating on fresh water that will hold an automobile of mass 1100 kg just above the surface of the
water? Assume the centers of mass of the car and the ice are vertically aligned. Take the
densities of water and ice to be 998 kg/m3 and 917 kg/m3, respectively.
A. 3.7 m2
B. 444 m2
C. 46 m2
D. no area is large enough
E. area cannot be determined from the information given
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Physics 213 Fall 2003 Midterm Form D
 
7. When you are 4.10 m from a point sound source, the sound level is 60.0 dB. How far away from
the same source must you be for the sound level to be 50.0 dB?
A. 410 m
B. 6.76 m
C. 13.0 m
D. 41.0 m
E. 1.29 m
8. A stretched wire of length 1.0 m is clamped at both ends. It is plucked at its center as shown. The
three longest wavelengths in the wire are (in meters):
A. 1, 0.5, 0.33
B. 1, 0.67, 0.5
C. 4, 2, 1
D. 2, 0.67, 0.4
E. 2, 1, 0.5
9. An iron anchor of density 7870 kg/m3 appears 300 N lighter in water (ρwater = 1000 kg/m3) than
in air. What is the weight of the anchor in air?
A. 1.6 N
B. 2.4 x 103 N
C. 1.6 x 103 N
D. 2.4 N
E. 2.4 x 102 N
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Physics 213 Fall 2003 Midterm Form D
 
10. In the figure, wave 1 consists of a rectangular peak of height 4 units and width d, and a
rectangular valley of depth 2 units and width d. The wave travels to the right along an x-axis.
Choices 2, 3 and 4 are similar waves, with the same heights, depths and widths that travel to the
left, one after another, along the same x-axis as wave 1. With which choice will the interference
give, for an instant, the deepest valley, a flat line and a level peak 2d wide, respectively?
A. 4, 2, 3
B. 2, 4, 3
C. 4, 4, 3
D. 3, 4, 3
E. due to superposition, none of these interference patterns can occur.
11. A ping-pong ball is placed in an inverted funnel as shown. When air is blown at sufficiently high
velocity into the narrow end of the funnel, the ping-pong ball:
 
A. remains in place due to Bernoulli's law, which states that the higher the air velocity, the lower
the pressure.
B. remains in place due to the slightly higher atmospheric pressure below the ball given by
ρairgh, where h is the diameter of the ball.
C. flies out due to Bernoulli's law which states that the higher the air velocity, the lower the
pressure.
D. flies out due to the pressure provided by the gust of air.
E. remains in place due to Bernoulli's law, which states that the higher the air velocity, the higher
the pressure.
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Physics 213 Fall 2003 Midterm Form D
 
12. A standing wave on a stretched string results from the interference of two traveling waves. Which
of the following wave properties is not the same for the two traveling waves that interfere to
produce the standing wave?
A. the wave speed
B. the frequency
C. the amplitude
D. the direction of travel
E. all of the above properties must be the same to produce a standing wave.
13. If the speed of sound is 340 m/s, the two lowest frequencies of an 0.5 m organ pipe, closed at
one end, are approximately:
A. 170 and 510 Hz
B. 340 and 680 Hz
C. 340 and 1020 Hz
D. 57 and 170 Hz
E. 170 and 340 Hz
14. A woman is running at speed 5 m/s toward a man who is singing a note of frequency 1,000 Hz.
What is the frequency she measures? The speed of sound in air is 330 m/s.
A. 1015.4 Hz
B. 1015.2 Hz
C. 1330.6 Hz
D. 1335.0 Hz
E. 985.1 Hz
15. You are in quicksand that has a density 1.9 times that of your body. What percentage of the
volume of your body will be above the surface of the quicksand?
A. 60 %
B. 40 %
C. 47 %
D. 6 %
E. 53 %
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Physics 213 Fall 2003 Midterm Form D
 
16. The figure shows the stress versus strain plot for an aluminum wire (E = 70 x 109 N/m2) that is
stretched by a machine pulling in opposite directions at the two ends of the wire. The wire has an
initial length of 0.5 m and an initial cross-sectional area of 2.0 x 10-6 m2. How much work does
the force from the machine do on the wire to produce a strain of 1.00 x 10-3?
A. 70 mJ
B. 140 mJ
C. 0 mJ
D. 35 mJ
E. 17.5 mJ
17. Fresh water of density ρ = 1000 kg/m3 is behind a reservoir dam that is 15 m deep. A horizontal
pipe 4.0 cm in diameter passes through the dam 6.0 m below the water surface, as shown in the
figure. A plug secures the pipe opening. The magnitude of the frictional force between the plug
and the pipe wall is:
A. 199 N
B. 295 N
C. 1795 N
D. 74 N
E. none of the above
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Physics 213 Fall 2003 Midterm Form D
 
18. The figure depicts different situations wherein a source of sound (S) and a detector (D) move with
respect to each other. The speeds of the detector and the source are equal to each other and are
identical in all situations. Rank the situations in order of decreasing frequency detected by the
detector.
 
S D 
A 
S D 
B 
S D 
C 
S D 
D 
A. (A = D) > B > C
B. B > (A = D) > C
C. (A = D) > C > B
D. C > (A = D) > B
E. C > B > (A = D)
19. A physics student drops a vibrating 440-Hz tuning fork down an empty elevator shaft. When the
student hears a frequency of 420 Hz, how far has the tuning fork fallen? The speed of sound in air
is 330 m/s.
A. 11.5 meters
B. 15.7 meters
C. 15.0 meters
D. 12.6 meters
E. 20.0 meters
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Physics 213 Fall 2003 Midterm Form D
 
20. Two isotropic sources of sound, S1 and S2, emit waves in phase at a wavelength 0.50 m. As
shown in the figure, they are separated by a distance D = 1.75 m. If we move a sound detector
around a large circle with radius r>>D and centered at the midpoint between the sources, at how
many points do waves arrive at the detector exactly in phase? You may wish to consider two
"extreme" situations in the process of answering this question - on the large circle directly above
the two sources, and on the large circle on a line directly to the right (or left) of the two sources.
 S2 S1 
D 
A. 7
B. 16
C. 2
D. 8
E. 14
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Answer Key for Test "P213MidtermFa03.tst", 9/20/2004
No. in
Q-Bank
No. on
Test Correct Answer
68 30 1 C
69 3 2 B
68 25 3 E
68 26 4 E
68 28 5 C
68 32 6 C
70 13 7 C
69 2 8 D
68 29 9 B
69 25 10 C
68 33 11 A
69 10 12 D70 16 13 A
70 3 14 B
68 31 15 C
67 12 16 D
68 27 17 D
70 17 18 D
70 6 19 D
69 24 20 E
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