Physics Chapter 13/14

The wavelength of a traveling wave can be calculated if one knows the:

frequency and speed.

Comparing the speed of sound in liquids, gases, and solids, the speed of sound is usually lowest in ____ and highest in ____.

gases, solids

If the air temperature decreases, how does the resonant frequency in a pipe closed at one end change?

it decreases.

Three identical springs each have the same spring constant k. If these three springs are attached end to end forming a spring three times the length of one of the original springs, what will be the spring constant of the combination?

k/3

Material 1 has Young's modulus Y1 and density ρ1, material 2 has Young's modulus Y2 and density ρ2, and material 3 has Young's modulus Y3 and density ρ​3. If Y1 > Y2 > Y3 and if ρ1 < ρ2 < ρ​3, which material has the highest speed of sound?

material 1

A pendulum on the Earth has a period T. The acceleration of due to gravity on Mars is less than that on the Earth, and the acceleration due to gravity on the Moon is even less. Where would the period of an identical pendulum be the least?

on the Earth

When I stand halfway between two speakers, with one on my left and one on my right, a musical note from the speakers gives me constructive interference. How far to my left should I move to obtain destructive interference?

one-fourth of a wavelength

Which of the following is an example of a longitudinal wave?

sound wave in air

If the tension on a guitar string is increased by a factor of 3, the fundamental frequency at which it vibrates is changed by what factor?

square root 3

If a simple harmonic motion is described by x = 3 cos(πt), starting from t = 0 s, what is the first occurrence of a value of t for which x = 0? Assume SI units.

t = (1/2) s

When an object is moving in simple harmonic motion, which of the following is at a minimum when the displacement from equilibrium is zero?

the magnitude of the acceleration

For a mass suspended on a spring in the vertical direction, the time for one complete oscillation will depend on:

the time doesn't depend on any of the above.

Consider a vibrating string that makes a sound wave that moves through the air. As the guitar string moves up and down, the air molecules that are a certain horizontal distance from the string will move

toward and away from the guitar string.

When car shock absorbers wear out and lose their damping ability, what is the resulting oscillating behavior?

underdamped

Wave #1 has frequency f1 and wavelength λ1. Wave #2 has frequency f2 = 6 f1 and wavelength λ2 = 2λ1. How does the speed v2 of wave #2 compare with the speed v1 of wave #1?

v2 = 12v1

If the frequency of a traveling wave train is increased by a factor of three in a medium where the speed is constant, which of the following is the result?

wavelength is one third as big

A mass on a spring vibrates in simple harmonic motion at a frequency of 8.0 Hz and an amplitude of 2.0 cm. If a timer is started when its displacement is a maximum (hence x = 2.0 cm when t = 0), what is the speed of the mass when t = 3.0 s?

zero

A 0.30-kg object is oscillating on a spring with a spring constant of k = 22.0 N/m. What is the potential energy of the system when the object displacement is 0.035 m, exactly half the maximum amplitude?

0.013 J

Waves propagate at 7.40 m/s along a stretched string. The end of the string is vibrated up and down once every 2.25 s. What is the wavelength of the waves that travel along the string?

16.7 m

What is the speed of sound in air at a temperature of -110 °F?

279 m/s

The position of a 0.64-kg mass undergoing simple harmonic motion is given by x = (0.160 m) cos (πt/16). What is its period of oscillation?

32 s

Assuming that the wave speed varies little when sound waves are traveling through a material that suddenly changes density by 10%, what percentage of the incident wave intensity is reflected?

< 1%

A series of ocean waves, 7.0 m between crests, move past at 4.0 waves/s. Find their speed.

NOT--11.0 m/s

When a sine wave is used to represent a sound wave, the crest corresponds to

condensation.

As a train starts from rest and then accelerates down the track, coming toward me faster and faster, the speed of the sound waves coming toward me will be

equal to the normal speed of sound in air.

Which of the following best describes a sound level of intensity 1 W/m2?

extremely loud

If a wave pulse is reflected from a free boundary, which of the following choices best describes what happens to the reflected pulse?

remains upright

Consider two identical and symmetrical wave pulses on a string. Suppose the first pulse reaches the fixed end of the string and is reflected back and then meets the second pulse. When the two pulses overlap exactly, the superposition principle predicts that the amplitude of the resultant pulses, at that moment, will be what factor times the amplitude of one of the original pulses?

0

Suppose a 0.70-kg mass on a spring that has been compressed 0.26 m has elastic potential energy of 2.20 J. How much further must the spring be compressed to triple the elastic potential energy?

0.19 m

A simple pendulum has a mass of 0.202 kg and a length of 1.00 m. It is displaced through an angle of 31.4° and then released. After a time, the maximum angle of swing is only 10.0°. How much energy has been lost to friction?

0.260 J

A child sits on a swing supported by ropes of length 2.0 m. With what frequency will she need to apply the driving force to maintain swinging?

0.35 Hz

A sound wave has a frequency of 850 Hz. What is the sound wave's wavelength if the air temperature is 26.0 °C?

0.41 m

A 0.30-kg block rests on a frictionless level surface and is attached to a horizontally aligned spring with a spring constant of 52.0 N/m. The block is initially displaced 3.20 cm from the equilibrium point and then released to set up a simple harmonic motion. What is the speed of the block when it passes through the equilibrium point?

0.421 m/s

A 0.38-kg block rests on a level surface and is attached to a horizontally aligned spring with a spring constant of 55.0 N/m. The block is initially displaced 4.8 cm from the equilibrium point and then released to set up a simple harmonic motion. A frictional force of 0.50 N exists between the block and surface. What is the speed of the block when it passes through the equilibrium point after being released from the 4.8-cm displacement point?

0.46 m/s

Two loudspeakers are placed side by side and driven by the same source at 525 Hz. A listener is positioned in front of the two speakers and on the line separating them, thus creating a constructive interference at the listener's ear. If one of the speakers is gradually pushed toward the listener, how far must it be moved to repeat the condition of constructive interference at the listener's ear? (The speed of sound = 340 m/s.)

0.65 m

If two adjacent frequencies of an organ pipe closed at one end are 385 Hz and 578 Hz, what is the length of the organ pipe? (vsound = 340 m/s)

0.88 m

What is the phase difference when two waves, traveling in the same medium, undergo constructive interference?

0°

I stretch a rubber band and "plunk" it to make it vibrate in its fundamental frequency. I then stretch it to four times its length and make it vibrate in the fundamental frequency once again. The rubber band is made so that quadrupling its length quadruples the tension and reduces the mass per unit length by a factor of 4. The new frequency will be related to the old by a factor of

1

Triple both the tension in a guitar string and its mass per unit length will result in changing the wave speed in the string by what factor?

1 (i.e., no change)

The frequency separating audible waves and ultrasonic waves is considered to be 15.0 kHz. What wavelength in air at room temperature is associated with this frequency? (Assume the speed of sound to be 225 m/s.)

1.50 cm

A mass of 0.40 kg, hanging from a spring with a spring constant of 82 N/m, is set into an up-and-down simple harmonic motion. What is the speed of the mass when moving through a point at 0.05 m displacement? The starting displacement of the mass is 0.10 m from its equilibrium position.

1.6 m/s

The Doppler shift of ultrasonic waves can measure the speed of blood in an artery. If the frequency of the stationary source is 95.0 kHz and the reflected sound has a Doppler shift of 210 Hz, what is the blood flow speed? (The speed of sound inside the body is 1 500 m/s.)

1.7 m/s

An ore car of mass 4 900 kg rolls downhill on tracks from a mine. At the end of the tracks, 13.5 m lower in elevation, is a spring with k = 410 000 N/m. How much is the spring compressed in stopping the ore car? Ignore friction.

1.78 m

If one-third of the members of a symphony orchestra are absent because of head colds, thus reducing the overall intensity of sound by 33%, what will be the reduction in the decibel level?

1.8 dB

A wave on a string has a wavelength of 0.90 m at a frequency of 600 Hz. If a new wave at a frequency of 300 Hz is established in this same string under the same tension, what is the new wavelength?

1.8 m

If I quadruple the mass per unit length of guitar string, its natural frequency changes by what factor?

1/ square root 4

An object is attached to a spring and its frequency of oscillation is measured. Then another object is connected to the first object, and the resulting mass is four times the original value. By what factor is the frequency of oscillation changed?

1/square root 4

A 2.5-m-long organ pipe is open at one end and closed at the other. Its fundamental tone has wavelength

10 m

A large spring requires a force of 130 N to compress it only 0.01 m. What is the spring constant of the spring?

13 000 N/m

What is the lowest frequency that will resonate in an organ pipe 5.00 m in length, closed at one end? The speed of sound in air is 340 m/s.

17.0 Hz

A speaker designed to emit spherical sound waves is producing a sound intensity of 8 W/m2 at a distance of 1 m from the speaker. What would be the intensity of this sound at a distance of 2 m from the speaker?

2 W/m2

Doubling the weight suspended vertically from a coil spring will result in a change in the displacement of the spring's lower end by what factor?

2.0

A tuning fork is sounded above a resonating tube (one end closed), which resonates at a length of 0.40 m and again at 1.2 m. If the tube length were extended further, at what point will the tuning fork again create a resonance condition?

2.0 m

If I0 = 10−12 W/m2 is the threshold of hearing, a sound with intensity I1 = 10−11 W/m2 will give a certain decibel level. Suppose a new sound has an intensity I2 = 2I12/I0. What is the new decibel level?

23 dB

A musical tone, sounded on a piano, has a frequency of 460 Hz and a wavelength in air of 0.50 m. What is the wave speed?

230 m/s

A mass of 0.40 kg, attached to a spring with a spring constant of 40 N/m, is set into simple harmonic motion. What is the magnitude of the acceleration of the mass when at its maximum displacement of 0.25 m from the equilibrium position?

25 m/s2

What is the intensity level of a sound with intensity of 6.0 × 10−10 W/m2? ( I0 = 10−12 W/m2 )

28 dB

If the speed of a wave on a violin string is 400 m/s, what will be the speed of the wave if the tension in the string is halved?

280 m/s

Spring #1 has spring constant 61.0 N/m. Spring #2 has an unknown spring constant, but when connected in series with Spring #1, the connected springs have an effective spring constant of 20.0 N/m. What is the spring constant for Spring #2?

29.8 N/m

I attach a 4.0-kg block to a spring that obeys Hooke's law and supply 3.4 J of energy to stretch the spring. I release the block; it oscillates with period 0.15 s. The amplitude is

3.1 cm.

If a radio wave has speed 3.00 × 108 m/s and frequency 94.3 MHz, what is its wavelength?

3.18 m

What is the intensity of a sound with a measured intensity level of 85 dB? (I0 = 10−12 W/m2)

3.2E-4 W/m2

The density of a certain metal solid is 6.5 × 103 kg/m3, and its Young's modulus is 10.0 × 1010 N/m2. What is the speed of sound in this metal?

3.9E+3 m/s

A plane is traveling at Mach 0.930 through air at a temperature of 0°C. What is the plane's speed? (Speed of sound at 0°C is 331 m/s.)

308 m/s

A 1.30-m string is held fixed at both ends. When driven by a 140-Hz source, the string vibrates in 4 distinct segments. What is the natural fundamental frequency of the string?

35.0 Hz

By what factor should the length of a simple pendulum be changed if the period of vibration were to be increased by a factor of three?

3^2

An astronaut sets up a pendulum on the Moon, where the acceleration due to gravity is 1/6 that of Earth. If she finds that she must push the pendulum with a frequency of 0.10 Hz to maintain a swinging motion, what is the length of the pendulum?

4.1 m

A simple pendulum has a period of 4.40 s. What is the pendulum length? (g = 9.80 m/s2)

4.81 m

A source of sound has an intensity I​1 and when its sound level is measured at a fixed distance the value found is 70 dB. The source then has its intensity increased to I​2 and when its sound level is measured at the same distance the value found is 96 dB. What is the ratio ​I​2/​I​1?

400

Transverse waves travel with a speed of 105 m/s along a taut copper wire that has a diameter of 2.28 mm. What is the tension in the wire? (The density of copper is 8.93 g/cm3.)

402 N

The lower A on a piano has a frequency of 30.0 Hz. If the tension in the 2.00-m-long string is 316 N and one-half wavelength occupies the string, what is the mass of the string?

43.9 g

You stand by the railroad tracks as a train passes by. You hear a 1 020-Hz frequency when the train approaches, which changes to 760 Hz as it goes away. How fast is the train moving? The speed of sound in air is 340 m/s.

49.7 m/s

For a wave traveling in a string, by what factor would the tension need to be increased to quadruple the wave speed?

4^2

Bats can detect small objects such as insects that are of a size approximately that of one wavelength. If bats emit a chirp at a frequency of 60 kHz, and the speed of sound waves in air is 335 m/s, what is the smallest size insect they can detect?

5.6 mm

A wave travels in a string at 58 m/s. A second string of 10% greater linear density has the same tension applied as in the first string. What will be the resulting wave speed in the second string?

55 m/s

A string is strung horizontally with a fixed tension. A wave of frequency 60.0 Hz is sent along the string, and it has a wave speed of 58.4 m/s. Then a second wave, one of frequency 120 Hz, is sent along the string. What is the wave speed of the second wave?

58.4 m/s

Quadrupling the power output from a speaker emitting a single frequency will result in what increase in loudness?

6.0 dB

If it takes 7 N to stretch a spring 8 cm and if the spring is then cut in half, what force does it take to stretch one of the halves 4 cm?

7 N

In the afternoon, the decibel level of a busy freeway is 85 dB with 90 cars passing a given point every minute. Late at night, the traffic flow is only 8 cars per minute. What is the late-night decibel level?

74 dB

A mass of 4.5 kg, resting on a horizontal frictionless surface, is attached on the right to a horizontal spring with spring constant 29 N/m and on the left to a horizontal spring with spring constant 60 N/m. If this system is moved from equilibrium, what is the effective spring constant?

89 N/m

A vibrating guitar string emits a tone simultaneously with one from a 495-Hz tuning fork. If a beat frequency of 5.00 Hz results, what is the frequency of vibration of the string?

Either choice b or c is valid.

An airplane flying with a constant speed flies from a warm air mass into a cold air mass. The Mach number will

INCREASE.

A note is being played on a string on a guitar. The string is then pushed to the side while still in contact with the same fret. What happens to the frequency of the note then played compared to the original note?

It is at higher frequency than the original note.

Material 1 has Young's modulus Y1 and density ρ​1, and material 2 has Young's modulus Y​2 and density ρ2. If Y1 is 30% more than Y​2 and ρ​1 is 30% less than ρ2, which material has the higher speed of sound and how much higher is it?

Material 1 has a speed of sound more than 35% higher than material 2.

Triple the mass of the bob on a simple pendulum will cause a change in the frequency of the pendulum swing by what factor?

NOT--1/3^2 1/3 3^2 3

An object moving in simple harmonic motion has an amplitude of 0.0450 m and a maximum acceleration of 40.0 m/s2. What is the frequency of the system?

NOT--11.9 Hz 14.9 Hz

A runaway railroad car, with mass 45.0 × 104 kg, coasts across a level track at 3.80 m/s when it collides with a spring-loaded bumper at the end of the track. If the spring constant of the bumper is 3.80 × 106 N/m, what is the maximum compression of the spring during the collision? (Assume the collision is elastic.)

NOT--2.10 m 2.62 m 1.85 m

The position of a 0.76-kg mass undergoing simple harmonic motion is given by x = (0.160 m) cos (πt/16). What is the maximum net force on the mass as it oscillates?

NOT--2.9E-2 N 2.4E-2 N

A mass on a spring vibrates in simple harmonic motion at a frequency of 4.20 Hz and an amplitude of 7.50 cm. If the mass of the object is 0.260 kg, what is the spring constant?

NOT--24.1 N/m

Two tuning forks sounding together result in a beat frequency of 4.00 Hz. If the frequency of one of the forks is 258 Hz, what is the frequency of the other?

NOT--266 Hz or 250 Hz 254 Hz or 262 Hz

Two vibrating tuning forks, held side by side, will create a beat frequency of what value if the individual frequencies of the two forks are 306 Hz and 300 Hz, respectively?

NOT--294 Hz 606 Hz

The speed of sound at 0°C is 331 m/s. What is the speed of sound at 10.0°C? (0°C = 273 K)

NOT--324 m/s 329 m/s 325 m/s

An ambulance with its siren on is heading due east along a straight road at 60 mph. A car is also moving along the same road. In which case will the driver of the car perceive the frequency of the siren to be lowest?

NOT--The car is moving east at 65 mph and is in front of the ambulance.

The wave-related quantity algebraically equivalent to 1/f is

T

How many nodes does a standing wave in a string have at the frequency of the sixth harmonic?

The answer is not given.

If one could transport a simple pendulum of constant length from the Earth's surface to the Moon's, where the acceleration due to gravity is one-sixth (1/6) that on the Earth, by what factor would the pendulum frequency be changed?

about 0.41

Which one of the following quantities is at a maximum when an object in simple harmonic motion is at its maximum displacement?

acceleration

A relatively new medical device that uses ultrasonics is referred to by the acronym CUSA. What does the letter A stand for?

aspirator

What phenomenon is created by two tuning forks, side by side, emitting frequencies, which differ by only a small amount?

beats