Exam 15: Traveling Waves and Sound

A wave on a string,mass per unit length of 0.2 g/cm,travels in the z direction with the string displaced in the x and y directions as described by the equations x = 5sin(kx - ωt)cm,and Y = 5cos(kx - ωt)cm. The wavelength and the wave velocity are γ = 11 cm and v = 6 cm/s respectively.What average power is transmitted along the string?

Find the wavelength of a train whistle heard by a fixed observer as the train moves toward the observer with a velocity of 50.0 m/s.A wind blows at 5.0 m/s from the observer to the train.The whistle has a natural frequency of 500.0 Hz.

A plane flies toward a stationary siren at 1/4 the speed of sound.Then the plane stands still on the ground and the siren is driven toward it at 1/4 the speed of sound.In both cases,a person sitting in the plane will hear the same frequency of sound from the siren.

As light passes from air into glass,its wavelength decreases and its frequency increases so that its speed does not change.

Which of the following is a FALSE statement?

Observer A is 2.0 m from a tiny light bulb and observer B is 8.0 m from the same bulb.The intensity of light from this bulb that A sees is 16 times as great as the intensity that B sees.

A wave pulse moves along a uniform string.The speed of this wave is constant but the speed of the particles of the string changes with time.

A string,30 cm long and having a mass of 45 g,is attached to a 810 Hz vibrator at one end.The other end of the string is fixed and the string is kept under tension.The vibrator produces a transverse wave in the string,whose amplitude is 7.0 mm,and that propagates with a velocity of 76 m/s.The energy of the wave is absorbed at the fixed end.In this situation,the tension in the string,in SI units,is closest to:

Find the speed of an ocean wave whose displacement is given by y = 3.7 cos(2.2x - 5.6t)where x and y are in meters and t is in seconds.

A uniform bar of metal,0.40 m long,with a diameter of 2.0 cm,has a mass of 1.1 kg. A 1.5 MHz longitudinal wave is propagated along the length of the bar.A wave compression traverses the length of the bar in 0.12 ms.The wavelength of the longitudinal wave in the metal,in mm,is closest to:

Which of the following increases when a sound becomes louder?

A weight W is hanging from a light vertical string.If a second weight W is added without stretching the string,the speed of pulses on this string will now be twice as great as it originally was.

The velocity of a longitudinal sound wave in an ideal gas is given by v = ,where γ is the ratio of the specific heat at constant pressure to that at constant volume,P is the pressure,and ρ is the mass density.Assuming an ideal gas with γ = 1.4 and ρ = 1.4 g/l at standard temperature and pressure,find the wavelength for a 2700 Hz sound wave.

You are generating traveling waves on a stretched string by wiggling one end.If you suddenly begin to wiggle more rapidly,you will cause the waves to travel faster down the string.

If you simultaneously send pulses of high frequency X rays and low frequency radio waves from Earth to the Moon,both waves will arrive at exactly the same time (assuming a vacuum between Earth and Moon).

The speed of sound in steel is 5000 m/s.What is the wavelength of a sound wave of frequency 660 Hz in steel?

Find the displacement of a simple harmonic wave of amplitude 6.44 m at t = 0.71 s.Assume that the wave number is 2.34 m^-1,the angular frequency is 2.88 rad/s,and that the wave is propagating in the +x direction at x = 1.21 m.

A motor drives a mechanism that produces simple harmonic motion at one end of a stretched cable such that the oscillation amplitude is 25.1 cm.What is the wave amplitude when the power of the motor is increased by 25.1%? Assume that the frequency oscillation and tension in the wire are unchanged.

Situation 15.1 A train is approaching a signal tower at a speed of 40 m/s.The train engineer sounds the 1000 Hz whistle and a switchman in the tower responds by sounding the 1200 Hz siren.The air is still and the speed of sound is 340 m/s. -In Situation 15.1,the frequency of the tower siren tone,heard by the engineer,in SI units,is closest to:

The howler monkey is the loudest land animal and can be heard up to a distance of 9.8 km.Assume the acoustic output of a howler to be uniform in all directions.The distance at which the intensity level of a howler's call is 25 dB,in SI units,is closest to: