The area of a typical eardrum is about 5.00 X 10-5 m2. (a) (Calculate the average sound power incident on an eardrum at the threshold of pain, which corresponds to an intensity of 1.00 W/m2. (b) How much energy is transferred to the eardrum exposed to this sound lor 1.00 mill?

Ultrasound of intensity 1.50102W/m2 is produced by the rectangular head of a medical imaging device measuring 3.00 cm by 5.00 cm. What is its power output?

Female Aedes aegypti mosquitoes emit a buzz at about 4.00102 Hz, whereas male A. aegypti mosquitoes typically emit a buzz at about 6.00102 Hz. As a female mosquito is approaching a stationary male mosquito, is it possible that he mistakes the female for a male because of the Doppler shift of the sound she emits? How fast would the female have to be traveling relative to the male for him to make this mistake? Assume the speed of sound in the air is 343 m/s.

The overall length of a piccolo is 32.0 cm. The resonating air column is open at both ends. (a) Find the frequency of the lowest note a piccolo can sound. (b) Opening holes in the side of a piccolo effectively shortens the length of the resonant column. Assume the highest note a piccolo can sound is 4 000 Hz. Find the distance between adjacent anti-nodes for this mode of vibration.

An ambulance with a siren (f=1.00kHz) blaring is approaching an accident scene. The ambulance is moving at 70.00 mph. A nurse is approaching the scene from the opposite direction, running at vo=7.00 m/s. What frequency does the nurse observe? Assume the speed of sound is v=343.00 m/s.

Three metal rods are located relative to each other as shown in Figure P17.68. where Ls = L1 + L2. The speed of sound in a rod is given by = Y/p, where Y is Youngs modulus for the rod and is the density. Values of density and Young's modulus for the three materials are 1 = 2.70 X 103 kg/m3, Y1 = 7.00 1010 N/m, 2 = 11.3 103 kg/m3, = 1.60 1010 N/m2. s = 8.80 103 kg/m3 Ys = 11.0 1010N/m2. If L3 = 1.50m, what must the ratio L1/L2if a sound wave is to travel the length of rods 1 and 2 in the same time interval required for the wave to travel the length of rod 3?

68 A single pulse, given by h(x - 5.01), is shown in Fig. 16-45 for t = 0. The scale of the vertical axis is set by h, = 2. Here x is in centimeters and t is in seconds. What are the (a) speed and (b) di- rection of travel of the pulse? (c) Plot h(x – 5t) as a function of x for 1 = 2 s. (d) Plot h(xr – 5t) as a func- tion of t for x = 10 cm. %3D %3! t= 0 Figure 16-45 Problem 68.

(III) You look directly overhead and see a plane exactly 1.45 km above the ground flying faster than the speed of sound. By the time you hear the sonic boom, the plane has traveled a horizontal distance of 2.0 km. See Fig. 12–38. Determine (a) the angle of the shock cone, 0, and (b) the speed of the plane and its Mach number. Assume the speed of sound is 330 m/s. FIGURE 12-38 Problem 69.

Assume a change at the source of sound reduces the wavelength of a sound wave in air by a factor of 20. (i) What happens to its frequency? O It increases by a factor of 400. O It increases by a factor of 20. O It is unchanged. O It decreases by a factor of 20. O It changes by an unpredictable factor. (ii) What happens to its speed? O It increases by a factor of 40o. O It increases by a factor of 20. O It is unchanged. O It decreases by a factor of 20. O It changes by an unpredictable factor.