Download May 1998 Physics 201

Physics 201
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May 1998
Physics 201
Final Exam Name_________________________
Do all work on these sheets. Try all questions; do not spend too much time on any one problem. Credit may be
subtracted if your work is disorganized, illegible, incomplete, lacks proper accuracy or if methods are not
clearly indicated. Bonus: Yes No
__________________________________________________________________________________________
Match the following (10 pts)
1. 10 log (I / I0)
A
Newton's Second Law
2. Power / Area
B
Torque
3. f (v + vo)
v - vs
4. dp
dt
5. Force / area
C
linear speed
D
Doppler effect
E
angular speed
6. mass / volume
F
Intensity
7. r x F
G
Stress
8.  = 0
H
Rotational Equilibrium
9. dx / dt
I
Intensity level
10. de / dt
J
Density
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Match the following (10 pts)
A. Archimedes' Principle
B. Lever arm C. Universal Gravitation
E. Simple Harmonic Motion F. Superposition Principle G. Intensity
I. Resonance J. Pascal's Principle
D. Doppler Effect
H. Hooke's Law
1. The stretching force is directly proportional to the springs displacement.
2. The change in frequency due to relative motion between source and observer.
3. Buoyant force equals weight of fluid displaced.
4. An external pressure exerted on a static, enclosed fluid is transmitted undiminished throughout the fluid.
5. Everybody attracts every other body with a force proportional to their masses, directed toward each other
and also proportional to the inverse square of their separation distance.
6. It occurs when the ratio of acceleration to displacement is constant.
7. The perpendicular distance from the axis of rotation to a line along which a force acts.
8. Time average rate at which energy is transported by the wave per unit area.
9. When two or more waves interfere, the height or displacement of the resultant wave at any point is equal to
the vector sum of the individual wave displacements.
10. The Tacoma Narrow Bridge collapse was caused by an engineering design error that did not effectively
treat this physical phenomenon.
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Multiple Choice (40 pts.)
____1. Sound waves are: (a) oscillating electromagnetic fields, (b) pressure waves in air, (c) due to air
molecules which move from the source to your ear, (d) transverse waves.
____2. An organ pipe of length 3.0m has one end closed. The two longest possible wavelengths for standing
waves inside the pipe are: (a) 6.0, 3.0m, (b) 12.0, 6.0m, (c) 12.0, 4.0m, (d) 9.0, 6.0m, (e) 3.0, 1.5m.
____3. If a net Torque is applied to an object, that object will experience which of the following? (a) a constant
angular velocity, (b) an angular acceleration, (c) a constant moment of inertia, (d) an increasing moment of
inertia.
____4. If 2 identical waves destructively interfere, the amplitude of the resulting wave is: (a) zero, (b) same as
one of original waves, (c) twice one of original waves, (d) four times that of one of original waves.
____5. Jim weighs 600N while on Earth, but on planet Mongo (same mass as Earth, but radius twice as large),
Jim's weight is: (a) 1200N, (b) 600N, (c) 300N, (d) 150N, (e) 100N.
____6. A decibel is a measure of a sound's: (a) frequency, (b) wavelength, (c) speed, (d) loudness.
____7. Adam's cello string 0.75 m long has a fundamental frequency of 220Hz. The speed of a wave on the
string is: (a) 165 m/s, (b) 220m/s, (c) 294 m/s, (d) 330 m/s.
____8. Chrissy's favorite “oldies" 45rpm record rotational velocity in rad/s is: (a) 45, (b) 283, (c) 0.75, (d) 4.7,
(e) 15.7.
____9. Given A = 2i + 3j + 2k, B = -3I + 4j the magnitude of A + B is: (a)45 + 4, (b) 8, (c) 2, (d) 54, (e)52
____10. A force F = 4.0i - 6.0j (N) acts on an object as it has a displacement r = 3.0i + 4.5j the work done is:
(a) -15J, (b) 15J, (c) 39J, (d) 12I – 27j (J), (e) –36k (J)
____11. An object in SHM obeys the equation: y = (0.50m) sin [(/2)t] It's period is: (a) 1.0s, (b) 2.0s, (c) 3.0s,
(d) 4.0s.
____12. The frequency of a wave increases. What happens to its speed? (a) increases, (b) remains the same,
(c) decreases, (d) cannot determine from information given.
____13. A pipe carrying water has a flow velocity of 1.0m/s and area of 20cm2. Assuming steady flow, what is
the velocity in 5cm2 constriction? (a) 0.25m/s, (b) 0.50m/s, (c) 1.0m/s, (d) 2.0m/s, (e) 4.0m/s.
____14. What is the buoyant force on a 0.25kg piece of aluminum of density 2700 kg /m3 when completely
submerged in water? (a) 2.4N, (b) 1.2N, (c) 0.91N, (d) 0.093N, (e) 2.45 x 10-3N.
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____15. A fast train approaches Steve waiting at a grade and sounds its horn. To Steve: (a) the wavelength
appears to be longer than if the train were at rest, (b) the frequency appears to be higher than if the train were at
rest, (c) the frequency appears to be lower than if the train were at rest.
____16. On a graph of force vs. displacement, what represents the work done by the force? (a) slope of the
curve, (b) the length of the curve, (c) area under the curve, (d) the tangent line to the curve.
____17. The cross product of 2 vector is non-zero when: (a) they are parallel, (b) they are 180 apart, (c) they
are perpendicular (d) both a & b.
____18. According to Newtonian physics, an object with no forces acting on it must: (a) fall, (b) eventually
come to rest, (c) be at rest, (d) either be at rest or have constant velocity, (e) have a constant, non-zero
acceleration.
____19. Ignoring air resistance, the horizontal component of a projectile’s acceleration: (a) is zero, (b) remains
a non-zero constant, (c) continually increases, (d) continually decreases.
____20. The number of overtones and their relative intensities give all instruments their own characteristic
sound. This sentence is describing (a) interference, (b) quality, (c) resonance, (d) standing waves.
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Problem: (15 points each)
1. Missy encounters Jim, Brian, and Nick. Each wants to take him home to study physics and so begin to pull
him. If the forces they exert are: Jim 120N at 0o, Brian 200 N at 60o, and Nick 150N at 225o. (a) What are
the components of each force? (b) What is the resultant force on Missy (c) What force does Missy need to
exert to remain at rest?
2. Kevin's rock band produces a sound level of 105dB at a distance of 20m from the center of the band.
Assuming the band radiates sound equally into hemisphere. (a) What is the intensity at 20m? (b) What is the
sound power output of the band?
1. A traveling wave on Andy's guitar has the form y = 0.10 sin (36 t + 3/7  x) meters.
Calculate: (a) amplitude, wavelength, period, frequency of this wave, (b) its velocity of propagation, (c) the
equation for its particle velocity.
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4.
Omotoyo enjoys bird watching at Hawk Mountain. She observes a hawk flying directly away from her
and directly toward a cliff emit a shrill cry of frequency 800Hz. (a) What frequency does she hear directly from
the bird? (b) What frequency does she hear in the echo that is reflected from the cliff? (c) How many beats are
heard? Take speed of sound as 340 m/s.
5.
Mike's motor uses a rope to pull a 50.0kg crate of apples up a 10.0m long ramp. The top of the ramp is
6.0m above the ground and the coefficient of kinetic friction between ramp and crate is 0.70. What is the
tension in the rope if the crate is moving at constant speed?
6.
A sunken ship (Edmund Fitzgerald) in Lake Erie has a mass of 500,000 kg & is completely water filled.
Steve wants to float it using air bags inflated inside the hull. What volume of air is needed? Density of steel is
7800 kg/m3; air is 1.29 kg/m3.