Excursions in Physics
PHY 3050G
Third Hour Exam

March 27, 2002


For every question, also consider as a possible answer
E) none of the above

Possibly useful information:
v = Dx/Dt p = m v T = 2
a = Dv/Dt PE = m g h T = 2
v = vi + a t PE = (1/2) k x2 v =
x = xi + vi t + (1/2) a t2 KE = (1/2) m v2 F = – k x
v = r w F = – k x fb = | f1 - f2 |
F = m a Ei = Ef v = (freq) x (wavelength)
F12 = - F21 pi = pf L = [n] x [wavelength/2]
w = mg F = Dp/Dt
g = 9.8 m/s2 10 m/s2


For every question, also consider as a possible answer
E) none of the above

1. Increasing the amplitude of a simple pendulum makes its frequency
A) longer
B) shorter
C) unchanged

2. Increasing the mass of a simple pendulum makes its frequency
A) longer
B) shorter
C) unchanged

3. Increasing the length of a simple pendulum makes its frequency
A) longer
B) shorter
C) unchanged

4. Increasing the amplitude of a mass-and-spring simple harmonic oscillator makes its period
A) longer
B) shorter
C) unchanged

5. Increasing the mass of a mass-and-spring simple harmonic oscillator makes its period
A) longer
B) shorter
C) unchanged

6. A mass-and-spring simple harmonic oscillator has maximum kinetic energy
A) at its equilibrium position
B) when its displacement equals its amplitude
C) half way between equilibrium and amplitude
D) two-thirds of the way between equilibrium and amplitude

7. A mass-and spring simple harmonic oscillator has maximum potential energy at
A) at its equilibrium position
B) when its displacement equals its amplitude
C) half way between equilibrium and amplitude
D) two-thirds of the way between equilibrium and amplitude

8. The frequency of a mass-and-spring simple harmonic oscillator is independent of its
A) mass.
B) spring constant.
C) amplitude.
D) all of the above.

9. The period of a simple pendulum depends upon its
A) mass
B) amplitude
C) length
D) all of the above

10. The period of a certain simple harmonic oscillator is 0.2 s; its frequency is
A) 0.5 Hz
B) 5.0 Hz
C) 50.0 Hz
D) 500 Hz

11. Ordinary household electricity is alternating current with a frequency of 60 Hz. Its period is
A) 60 cycles per second
B) 120 cycles per second
C) 0.0167 s
D) 0.0583 s

12. If you apply a force to an oscillator at its natural frequency, you will produce motion
A) at exactly twice that frequency
B) at exactly one-half that frequency
C) with large amplitude
D) with an amplitude that damps out or gets smaller.

13. There are "signals" of many different frequencies coming into the antenna of your radio. Only the one with a particular frequency is amplified and produces the sound you listen to. This is an example of
A) damping
B) amplitude degeneration
C) timbre or quality
D) resonance

14. If a carefully calibrated pendulum were over a very large oil deposit, where the acceleration due to gravity is slightly decreased, what would happen to the pendulum's period?

A) increase
B) stay the same
C) decrease

15. Where is the speed of a simple harmonic oscillator zero?
A) at its equilibrium position
B) when its displacement equals its amplitude
C) half way between equilibrium and amplitude
D) two-thirds of the way between equilibrium and amplitude

16. Like a transverse wave, a longitudinal wave has
A) an amplitude
B) a frequency
C) a wavelength
D) all of the above

17. Which of the following is a longitudinal wave?
A) light
B) wave on a string
C) sound
D) all of the above



18. The individual vibrations or disturbances of a longitdinal wave move
A) in the same direction as the wave itself
B) perpendicular to the wave itself

19. A wave has a frequency of 50 Hz and travels 25 m in one second. It has
A) a wave speed of 25 m/s and a wavelength of 0.5 m.
B) a wave speed of 25 m/s and a wavelength of 2.0 m
C) a wave speed of 200 m/s and a wavelength of 2.0 m
D) a wave speed of 200 m and a wavelength of 0.5 m

20. Unlike billiard balls, waves can pass through each other. This is known as
A) echolocation.
B) resonance.
C) superposition.
D) interactive collisions.

21. For standing waves, antinodes
A) are half a wavelength apart
B) have the greatest amplitude
C) alternate with nodes
D) all of the above

22. For standing waves on a string,
A) a node is located at each end
B) a whole number times half the wavelength equals the length of the string
C) the whole "pattern" of standing waves occurs only for certain frequencies
D) all of the above

23. If you listen to the horn on a railroad engine as it approaches you and then recedes from you, you will notice a change in the pitch. You will hear
A) the approaching train sound lower and then go higher as it leaves.
B) the approaching train sound louder and then become softer as it leaves.
C) the approaching train sound higher and then go lower as it leaves.
D) the approaching train sound softer and then become louder as it leaves.

24. On a string that is 1.0 m long, standing waves may be formed with the following wavelengths:
A) 1.0 m, 2.0 m, 3.0 m
B) 1.0 m, 2.0 m, 4.0 m
C) 3.0 m, 1.5 m, 0.75 m
D) 2.0 m, 1.0 m, 0.5 m

25. Standing waves can occur when
A) the frequency equals the wavelength
B) the amplitude exceeds the wavelength
C) a wave is reflected back on itself
D) a wave's period equals its wavelength

26. A node is
A) always in the middle of a standing wave
B) a position of maximum amplitude
C) a position of minimum amplitude
D) equal to the fundamental frequency
27. Light and sound are both waves. You can see a ringing bell inside an evacuated glass container but you can not hear it. This is because
A) of resonance
B) light travels faster than sound
C) sound requires air to be transmitted and light does not
D) light passes through glass but sound does not

28. A bobber on a fishing line oscillates up and down three times per second as waves pass by. The waves have a frequency of
A) (1/3) Hz
B) 3 Hz
C) (1/3) sec
D) 3 sec


29. If there were a gigantic explosion on our moon we would not hear it because sound

A) is a transverse wave
B) requires a medium to travel or to “wave”
C) is resonant
D) must be polarized to travel such a great distance

30. If you put your fingertip in a pool of water and repeatedly move it up and down, you will create circular water waves that move out from that point. What will happen to the wave-length of these waves if you move your finger up and down more slowly (or less frequently)?
A) increase
A decrease in frequency means an increase in wavelength.
B) remain the same
C) decrease

31. A “sonic boom” occurs
A) only at the moment an aircraft “breaks” the sound barrier.
B) when the cone of high pressure following behind a supersonic airplane encounters people or buildings.
C) when there is a temperature inversion.
D) only over water.

32. "Supersonic" means
A) lower than the range of human hearing
B) higher than the range of human hearing
C) faster than the speed of sound
D) slower than the speed of sound

33. "Ultrasonic" means
A) lower than the range of human hearing
B) higher than the range of human hearing
C) faster than the speed of sound
D) slower than the speed of sound

34. "Infrasonic" means
A) lower than the range of human hearing
B) higher than the range of human hearing
C) faster than the speed of sound
D) slower than the speed of sound
35. Bats and dolphins use echolocation to navigate or the find food or to find their way without relying on sight. The frequencies they use are
A) supersonic
B) infrasonic
C) ultrasonic
D) microsonic

36. If you double the frequency of a sound wave, you also double its
A) wavelength
B) speed
C) amplitude
D) all of the above

37. The range of human hearing is about
A) 10 Hz to 100 Hz
B) 50 Hz to 500 Hz
C) 50 Hz to 20 kHz
D) 1 kHz to 100 kHz

38. Sound travels fastest in
A) air (a gas)
B) water (a liquid)
C) steel (a solid)
D) vacuum

39. The speed of sound in air depends upon
A) wavelength
B) frequency
C) temperature
D) amplitude

40. Increasing the length of a vibrating string will
A) decrease its resonance frequency
B) decrease its amplitude
C) increase its amplitude
D) increase its resonance frequency

41. Ella Fitzgerald made commercials for Memorex in which she used her voice to break a wine glass. This is an example of
A) echolocation
B) reflected sound
C) ultrasonic frequencies
D) resonance

42. Beats are heard when two sounds have
A) nearly the same amplitude
B) nearly the same frequencies
C) twice the amplitude
D) exactly twice the wavelength



43. If you listen to the horn on a railroad engine as it approaches you and then recedes from you, you will notice a change in the pitch. You will hear
A) the approaching train sound lower and then go higher as it leaves.
B) the approaching train sound louder and then become softer as it leaves.
C) the approaching train sound higher and then go lower as it leaves.
D) the approaching train sound softer and then become louder as it leaves.

44. The "pitch" of a sound is determined by its
A) overtones frequencies
B) harmonics frequencies
C) fundamental frequency
D) resonance frequencies

45. The quality or timbre -- the distincitive characteristic -- of a sound is determined by its
A) overtones or harmonics
B) amplitude or loudness
C) attack or decay
D) fundamental frequency

46. You hear beats with a frequency of 3 Hz when you strike a tuning fork that vibrates at 256 Hz and a chime. The chime has a frequency of
A) 3 x 256 Hz = 768 Hz
B) 253 Hz
C) 250 Hz
D) (256 / 3) Hz = 85.3 Hz

47. The fundamental frequency of a violin string is 440 hertz. The frequency of its second harmonic is
A) 110 Hz
B) 220 Hz
C) 440 Hz
D) 880 Hz

48. Consider a musical note of 440 hertz ("concert 'A'"). Two octaves higher is represented by a musical note of
A) 220 Hz
B) 880 Hz
C) 1320 Hz
D) 1760 Hz.

49. The lowest frequency present in a sound determines its
A) pitch.
B) amplitude.
C) beat frequency.
D) quality or timbre.

50. Suppose you play a note of a certain pitch on a violin. You can produce a lower-pitched note by
A) shortening the length of the string that is allowed to vibrate
B) increasing the tension of the string
C) decreasing the linear mass density of the string
D) lengthening the part of the string that vibrates.



Add’l questions:

*. The loudness of a sound is associated with its
A) frequency.
B) wavelength.
C) velocity.
D) amplitude.

*. Sound that we might describe as “noise” has
A) a large amplitude.
B) no period.
C) a high frequency.
D) a short wavelength.

*. The harmonics present in a sound determine its
A) pitch.
B) amplitude.
C) beat frequency.
D) quality or timbre.

*. The lowest frequency present in a sound determines its
A) pitch.
B) amplitude.
C) beat frequency.
D) quality or timbre.

*. Bats and dolphins emit high-pitched sound and use its reflection to find food and to navigate without sight. This is known as
A) echolocation
B) absorbed sound
C) infrasonic frequencies
D) resonance

*. If you listen to the horn on a railroad engine as it approaches you and then recedes from you, you will notice a change in the pitch. This is described as the
A) Newton’s sound effect.
B) Doppler effect.
C) Radar-gun syndrome.
D) Sonic boom.

*. If you listen to the horn on a railroad engine as it approaches you and then recedes from you, you will notice a change in the pitch. You will hear
A) the approaching train sound lower and then go higher as it leaves.
B) the approaching train sound louder and then become softer as it leaves.
C) the approaching train sound higher and then go lower as it leaves.
D) the approaching train sound softer and then become louder as it leaves.

*. A “sonic boom” occurs
A) only at the moment an aircraft “breaks” the sound barrier.
B) when the cone of high pressure following behind a supersonic airplane encounters people or buildings.
C) when there is a temperature inversion.
D) only over water.

*. When a boat goes faster than the speed of surface waves on a lake it produces
A) breakers that have a frequency that is twice that of the boat’s.
B) breakers that have a frequency the same as the boat’s.
C) “white caps” with “froth” at the top of the waves.
D) a large bow wave.

*. Unlike billiard balls, waves can pass through each other. This is known as
A) echolocation.
B) resonance.
C) superposition.
D) interactive collisions.

*. When two waves interfere and cause a larger amplitude, this is known as
A) echolocation.
B) destructive interference.
C) constructive interference.
D) resonance.

*. Ultrasound can be used to make images of the insides of a body. Ultrasound has the advantage of providing high resolution due to its
A) small wavelength.
B) very long wavelength.
C) small amplitude.
D) low frequency.

*. The frequency of a mass-and-spring simple harmonic oscillator is independent of its
A) mass.
B) spring constant.
C) amplitude.
D) all of the above.

14. If a carefully calibrated pendulum were over a very large oil deposit, where the acceleration due to gravity is slightly decreased, what would happen to the pendulum's period?
A) increase
B) stay the same
C) decrease


37. The range of human hearing is about
A) 10 Hz to 100 Hz
B) 50 Hz to 500 Hz
C) 50 Hz to 20 000 Hz
D) 1 000 Hz to 100 000 Hz

40. Increasing the length of a vibrating string will
A) decrease its resonance frequency
B) decrease its amplitude
C) increase its amplitude
D) increase its resonance frequency

41. Ella Fitzgerald made commercials for Memorex in which she used her voice to break a wine glass. This is an example of
A) echolocation
B) reflected sound
C) ultrasonic frequencies
D) resonance

42. Beats are heard when two sounds have
A) nearly the same amplitude
B) nearly the same frequencies
C) twice the amplitude
D) exactly twice the wavelength

 
14. A wave has a frequency of 20 Hz and travels 5 m in one second. It has
A) a wave speed of 100 m/s and a wavelength of 4 m.
B) a wave speed of 100 m/s and a wavelength of 1/4 m.
C) a wave speed of 5 m/s and a wavelength of 1/4 m
D) a wave speed of 5 m/s and a wavelength of 4 m
 
15. A wave has a frequency of 32 Hz and travels 4 m in one second. It has
A) a wave speed of 100 m/s and a wavelength of 128 m.
B) a wave speed of 100 m/s and a wavelength of 1/8 m.
C) a wave speed of 4 m/s and a wavelength of 1/8 m
D) a wave speed of 4 m/s and a wavelength of 8 m
 
16. A wave has a frequency of 50 Hz and a wavelength of 0.5 m. It has a wave speed of
A) 2.5 m/s
B) 25 m/s
C) 50 m/s
D) 500 m/s
 
17. A wave has a frequency of 150 Hz and a wavelength of 0.3 m. It has a wave speed of
A) 2.0 m/s
B) 20 m/s
C) 45 m/s
D) 50 m/s
 
35. Suppose you play a note of a certain pitch on a violin. You can produce a lower-pitched note by
A) shortening the length of the string that vibrates
B) increasing the tension of the string (tightening the string)
C) decreasing the linear mass density of the string (using a "lighter" string)
D) increasing the length of the string that vibrates.

36. When a flute sound is viewed on an oscilloscope, the sound wave is very smooth. This is because
A) the amplitude is always small (flutes are quiet)
B) it has practically no overtones or harmonics
C) its fundamental frequency has a smaller amplitude than its second and third harmonics
D) its harmonics get larger and larger
 
37. When a piano sound is viewed on an oscilloscope, the sound wave is complex. This is because
A) the amplitude is always large (pianos are loud)
B) it has practically no overtones or harmonics
C) it has many overtones or harmonics
D) its has only even-numbered overtones or harmonics


44. As an oscillator’s amplitude decreases, we describe this by saying the oscillator is
A) at resonance
B) driven
C) damped
D) continuous

45. You hear thunder some time after seeing the lightning that caused it because
A) light can not travel through a vacuum
B) light travels faster than sound
C) sound travels faster than sound
D) sound can not travel through air

47. If there were a gigantic explosion on our moon we would not hear it because sound
A) is a transverse wave
B) requires a medium to travel or to “wave”
C) is resonant
D) must be polarized to travel such a great distance

48. Sir Isaac Newton measured the speed of sound
A) extremely accuratly; his measurements were the best at that time
B) using water clocks and an assistant on neighboring hills outside Cambridge
C) to ensure that clocks at sea would keep accurate time
D) to give evidence to his theory of gravitation

49. The speed of a simple pendulum is zero where the displacement is
A) zero
B) one-half the amplitude
C) the amplitude
D) twice the amplitude


PHY 3050G, Third hour exam, 3/27/2002 — p #