Q4) Doppler uses ultrasound to measure blood flow velocities. Suppose that the device emits sound at a frequency of 3.2MHz, and that the speed of sound in human tissue is m/s 1540). What is the expected pulse rate if blood is flowing in the arteries of the large leg at a speed of 3 cm/s away from the source of the sound? 1260Hz 126Hz 12.6Hz O 12.6KHz 126KHZ O 1260KHz 1.26MHz

Oil explorers often set off explosives to make loud sounds, then listen for the echoes from underground oil deposits. Geologists suspect that there is oil under 520-m-deep Lake Physics. It's known that Lake Physics rests on top of solid granite. The speed of sound in water is 1480 m/s and the speed of sound in granite is 6000 m/s.   a. If an explosion is created at the surface of the lake, what time after the explosion do the explorers expect to hear an echo from the bottom of the lake in seconds?   t=0.703s   b. In addition to the expected echo from the bottom of the lake, explorers also detect a faint echo 0.960 s after exploding the dynamite at the lake surface. If it's really oil, how deep will they have to drill through the granite to reach it in meters?

10. If the intensity for 5 bugs is 6 x 10-12 W/m² then what is the intensity for 1 bug? For 3 bugs? 11. If 1 bug makes a sound of 8 dB then what will 25 bugs sound like? 12. If 4 bugs make a sound of 14 dB then what will 25 bugs sound like?

= frequency X wavelength 1. A boy throws a rock into the lake creating waves with a frequency of 10.0 Hz and a wavelength of 20.0 m. What is the speed of the wave? Ich

10 B. Suppose that you put your left ear down against a railroad track, and your friend one kilometer away strikes the track with a hammer. a). How much sooner will the sound get to your left ear than to your right ear? (The speed of sound is about 5950 m/s in steel and 340 m/s in air.) b). Draw a sketch to support your results and include given information, formulas and calculations. Your answer

10. The speed of sound in air is 343.2 m/s at 20 °C. You design experiments using three different types of techniques and equipment to measure the speed of sound yourself. You collect the following sets of experimental data (four measurements, or trials, for each of your three techniques). Which trial provides good precision but poor accuracy? a. trial 1: 346 m/s, 356 m/s, 334 m/s, 329 m/s b. trial 2: 374 m/s, 373 m/s, 371 m/s, 373 m/s c. trial 3: 345 m/s, 344 m/s, 342 m/s, 341 m/s d. trial 1: 313 m/s, 333 m/s, 353 m/s, 363 m/s e. more than one of the above provides precision but not accuracy

4. A car, sounding its horn, is moving at v. =158.4km / h directly toward a stationary wall in still air. The speed of sound, in the air, is v=330.0 m/s. The horn produces sound at a frequency of f. =1000.Hz (ie. if the car were stationary, that is the frequency you would hear). a) What frequency is heard by an observer at rest at the wall (assume the car is moving straight toward the observer)? b.) What is the wavelength, in the still air, of the sound wave approaching the wall? c) What is the frequency of the reflected sound heard by an occupant of the car?

Tornado Siren. The frequency of a tornado siren is 920 Hz. If a cyclist  is moving toward the siren at 10 m/s in 15 °C air, which has a speed of sound of 340 m/s, what is the frequency that the cyclist observes?

Q2

7:25 a & Fll 19% YG The lower frequency limit of hearing for a particular human being is 25.3 Hz. What is the corresponding wavelength (in meters) for this frequency if the speed of sound in air is 343 m/s? Select one: а. 1.36 b. 0.07 c. None of the above d. 12.65 е. 13.6 II II