4) An audio speaker producing a steady sound at an outdoor concert is 40 ft away from you. If you move to a position where the speaker is 72 ft distant, by what factor will the amplitude of the sound change?

A_f

_{____ =}

A_i

5) Two children stretch a jump rope between them and send wave pulses back and forth on it. The rope is 4.9 m long, its mass is 0.30 kg, and the force exerted on it by the children is 35 N.

a) What is the linear mass density of the rope (in kg/m)?

(b)What is the speed of the waves on the rope (in m/s)?

6) A 1.8 Hz continuous wave travels on a Slinky. If the wavelength is 0.71 m, what is the speed of waves on the Slinky (in m/s)?

____m/s

7) A wave traveling 65 m/s has a wavelength of 2.6 m. What is the frequency of the wave (in Hz)? ______Hz

8) A steel cable with total length 24 m and mass 120 kg is connected to two poles. The tension in the cable is 5,314 N, and the wind makes the cable vibrate with a frequency of 2 Hz. Calculate the wavelength of the resulting wave on the cable.

_______m

9) In a student laboratory exercise, the wavelength of a 64,300 Hz ultrasound wave is measured to be 0.541 cm. Find the air temperature (in K). _____K

10) A person stands directly in front of two speakers that are emitting the same pure tone. The person then moves to one side until no sound is heard. At that point, the person is 9.15 m from one of the speakers and 9.17 m from the other. What is the frequency (in Hz) of the tone being emitted? (Assume air temperature to be 20C.)

_____Hz

11) A sonic depth gauge is placed 4.8 m above the ground. An ultrasound pulse sent downward reflects off snow and reaches the device 0.026 seconds after it was emitted. The air temperature is 20C.

(a)How far (in m) is the surface of the snow from the device? (Round your answer to at least three significant figures.)

(b)How deep (in m) is the snow?

12) A baseball fan sitting in the "cheap seats" is d = 135 m from home plate (see the figure below). How much time elapses between the instant the fan sees a batter hit the ball and the moment the fan hears the sound? (Assume the speed of sound is 344 m/s, and the vertical distance can be ignored.)

________s

13) Approximately how many times louder is a 170-dB sound than a 90-dB sound?

16) The force stretching the D string on a certain guitar is 174 N. The string's linear mass density is 0.003 kg/m.

What is the speed of waves on the string?

____m/s