Module 7 - Hooke’s Law, Waves on a String, Sound Waves in Air, Wave Speed and Intensity

Question 1

a block on the end of a horizontal spring is pulled from equilibrium at x=0 to x=A and released. through what total distance does it travel in one full cycle of its motion?

Answer 1

4A

Question 2

when an object moving in simple harmonic motion is at its maximum displacement from equilibrium, which of the following is at a maximum (magnitude)?

Answer 2

acceleration

Question 3

for a simple harmonic oscillator, which of the following pairs of vector quantities can’t both point in the same direction? (the position vector is the displacement from equilibrium)

Answer 3

position and acceleration

Question 4

which of the following statements is not true regarding a mass-spring system that moves with simple harmonic motion in the absence of friction?

Answer 4

the potential energy stored in the system is greatest when the mass passes through the equilibrium position

Question 5

for a wave on the ocean (simplify by assuming that this is purely transverse wave), the amplitude is:

Answer 5

one half the heigh difference between a crest and a trough

Question 6

a sinusoidal wave of wavelength λ travels along a stretched string. then the string is brought to rest and a second wave of wavelength 2λ is established on the same string (with the same applied tension). the wave speed of the second wave is:

Answer 6

same as that of the first wave

Question 7

a sinusoidal wave of wavelength λ travels along a stretched string. then the string is brought to rest and a second wave of wavelength 2λ is established on the same string (held under the same tension). the frequency of the second wave is:

Answer 7

half that of the first wave

Question 8

assume that a heavy rope is tied to a light rope. imagine a transverse wave that propagates from the light rope onto the heavy rope. for this wave, what will occur?

Answer 8

the wave speed will decrease

Question 9

the use of the term “sound waves” in air is meant to describe:

Answer 9

the pressure variations in the air

Question 10

raising the temperature of air will…

Answer 10

increase the speed of sound in the air

Question 11

someone is listening to a singer on the podium (speaker broadcast). listener walks closer to the podium. his final distance is half his initial, what will be the intensity of the singer’s voice that the person hear compared to initial intensity?

Answer 11

four times that of the first intensity

Question 12

two sounds of the same intensity are added together. the intensity level of the resulting sound (note that log(2) = 0.30)…

Answer 12

will be three decibels higher than the original sound