Physics 101.002                           Test 1          Answers                            September 20, 2007

 

Read each question and its set of answers very carefully.  There is only one best answer for each question.  Don’t be afraid to ask questions of me during the exam.  Just raise your hand if you have one. 

 

 

1.  The time required for a pendulum to make one complete vibration (oscillation) is called __________ a pendulum.

(a) the frequency of  

(b) the period of

(c) the wavelength of          

(d) the speed of

 

2.  Doubling the mass of a simple pendulum undergoing small oscillations does what to the period of the pendulum?

(a) increases it by square of 2       

(b) cuts it in half

(c) nothing                         

(d) doubles it

 

3.  Hertz (Hz) is a unit of

(a) sound                           

(b) wavelength

(c) frequency                     

(d) wave velocity

 

4.  The period of the second hand on a watch is (think carefully)

(a) 1 second                      

(b) 1 minute

(c) 1 hour                          

(d) 12 hours

(e) 24 hours

 

5.  How many vibrations per second are represented in a radio wave of 101 MHz?

(a) 101                     

(b) 101,000

(c) 101,000,000                  

(d) 1.01

 

6.  A wave will travel one wavelength during one period of vibration.

(a) True                   

(b) False

 

7.  A swing requires 10 seconds to complete 5 full swings.  What is the frequency in Hz for this swing?

(a) 1.0                      

(b) 5.0

(c) 0.5                      

(d) 10.0

(e) 2.0

 

8.  As the frequency of a wave of constant speed is increased, does the wavelength increase or decrease?

(a) increase                        

(b) decrease

(c) remains unchanged

 

9.  Six water waves pass by a floater on the surface of a pond in three seconds.  The wavelength of each wave is 2 centimeters.  What is the period of the waves in second(s)?

(a) 1/2                      

(b) 6

(c) 1/6                      

(d) 1/3

(e) 3

 

10. With _____ waves, the vibration of the particles of the medium is in the direction parallel to the motion of the wave.

(a) longitudinal         

(b) light

(c) transverse           

(d) more than one answer

 

11. One wavelength of a longitudinal wave is the distance between a compression (condensaton) and an adjacent rarefaction.

(a) True                   

(b) False

 

12. What kind of waves can show interference?

(a) water waves                  

(b) sound waves in air

(c) waves on a rope           

(d) all of the above

(e) none of the above

 

13. The part of a standing wave that is vibrating wildly is a (an)

(a) interference point          

(b) node

(c) compression                 

(d) crest

(e) antinode

 

14. While you are moving away from a stationary source of sound, the frequency of the sound you hear

(a) is greater than what the source emits

(b) is less than what the source emits

(c) is the same as what the source emits

 

15. Would a super-fast fish that is swimming faster than the speed of sound (in water) produce a sonic boom?

(a) Yes                     

(b) No

 

16. Flapping your hand back and forth as fast as you can produces                sound wave.

(a) a supersonic                 

(b) an ultrasonic

(c) an infrasonic                 

(d) a subsonic

 

17. A sound wave in air can best be described as

(a) a transverse wave          

(b) a longitudinal wave

(c) a standing wave            

(d) a shock wave

 

18. In a sound wave in air, the areas of high density of air molecules are called

(a) troughs                         

(b) rarefactions

(c) compressions               

(d) antinodes

 

19. Even though the moon is not a planet, it is often referred to as a “silent planet” because there is no atmosphere to transmit sound.

(a) True                   

(b) False 

 

20. Sound waves cannot travel in which of the following?

(a) air

(b) under water

(c) steel

(d) a vacuum

(e) sound can travel in all of the above

 

21. The speed of sound in a medium depends on

(a) the elasticity of the medium

(b) the temperature of the medium

(c) the density of the medium

(d) all of the above

(e) none of the above

 

22. When you see lightning and hear thunder 30 seconds later, how close is the lightning?  (One mile equals 5280 feet.)

(a) 2 mi                    

(b) 5 mi

(c) 3 mi                    

(d) 6 mi

 

23. An oceanic depth-sounding vessel surveys the ocean bottom with ultrasonic sound that travels 1530 m/s in seawater.  How deep is the water if the time for the sound to travel to the ocean floor and back is 2 s?

(a) 1530 m                         

(b) 3060 m

(c) 715 m                           

(d) none of the above

 

24. Sound travels faster on hot days than on cold days.

(a) True                   

(b) False

 

25. Why can the tremor of the ground from a distant explosion be felt before the sound of the explosion is heard?

(a) because the speed of sound in vacuum is less than the speed of sound in the ground

(b) because sound travels through air, but not through the ground, so you only feel vibrations

(c) because the speed of sound in earth is greater than speed of sound in air

 

26. Reverberation is due to multiple refractions of sound.

(a) True                   

(b) False

 

27. If the air above a large body of water is of uneven temperatures, then sounds may be heard for great distances over the water because of

(a) reflection                      

(b) refraction

(c) interference         

(d) none of the above

 

28. How do light waves differ from sound waves in air?

(a) light waves are transverse

(b) light waves carry more energy

(c) light waves are faster

(d) all of the above

(e) none of the above

 

29. In a classroom demo, the instructor struck a tuning fork and immediately touched it to the lecture table to show

(a) forced vibration            

(b) energy in sound

(c) resonance                     

(d) refraction of sound

 

30. A frequency at which an elastic object naturally tends to vibrate (so that minimum energy is required to produce a forced vibration or is required to continue vibration at that frequency) is called               frequency.

(a) a natural                        

(b) a forced

(c) a reverberation              

(d) an ultrasonic

 

31. When successive impulses are applied to a vibrating object in time with the natural frequency of the object

(a) reverberation occurs

(b) resonance occurs

(c) refraction occurs

(d) none of the above

 

32. What is the beat frequency when a 262-Hz and a 266-Hz tuning fork are sounded together?

(a) 264 Hz                         

(b) 10 Hz

(c) 4 Hz                   

(d) 528 Hz

 

33. The three characteristics of a musical tone are loudness, pitch, and timbre.

(a) True                   

(b) False

 

34. In air the wavelength of sound A is twice the wavelength of sound B.  How do the pitches of these sounds compare?

(a) the pitch of A is twice the pitch of B

(b) the pitch of B is twice the pitch of A

(c) the pitch is the same for both, it is the speed that is different

 

35. Loudness is most closely associated with which characteristic of a wave?

(a) amplitude                      

(b) frequency

(c) wavelength          

(d) speed

 

36. A 60 dB sound has an intensity two times greater than a 30 dB sound.

(a) True                   

(b) False

 

37. If a vibrating string is made shorter (as by holding a finger on it), what effect does this have on the pitch?

(a) it decreases         

(b) it increases

(c) it remains unaffected

 

38. If the fundamental frequency of a violin string is 440 Hz, what is the frequency in Hz of the first overtone?

(a) 1320                   

(b) 880

(c) 440

 

39. The distinguishing difference in sound produced when a piano and a trumpet play the same note is called

(a) forced resonance

(b) beats

(c) fundamental difference

(d) timbre

 

40. The third harmonic in a closed organ pipe corresponds to which overtone?

(a) third                    

(b) fourth

(c) second                         

(d) first