# physics

posted by
**Jon**
.

1)As a sound source moves away from a stationary observer, the number of waves will.

decrease

2)How fast should a car move toward you for the car's horn to sound 2.88% higher in frequency than when the car is stationary? The speed of sound is 343 m/s.

fs(v-vd/v-vs)

343(1/1-987/343)

A)4.5 m/s

B)7.3 m/s

C)9.6 m/s

D)11.8 m/s

I'm doing something wrong I got D (well I guessed D)

3)A car moving at 16.0 m/s, passes an observer while its horn is pressed. Find the difference between the frequencies of sound heard when the car approaches and when it recedes from the stationary observer. The velocity of sound is 343 m/s and the frequency of the sound of the car's horn is 583 Hz.

4)A boy is blowing a whistle of frequency 536 Hz and walking toward a wall with a speed of 1.64 m/s. What frequency of the reflected sound will the boy hear if the speed of sound is 343 m/s?