The Doppler effect causes a sound moving towards you to sound higher pitched and a sound moving away from you to sound lower pitched, like observed in listening to the car horn in the video. The equation for this is f = ( c c + v ) f 0 , where f is the observed frequency (pitch) of the sound, in Hertz c is the speed of sound, about 761 miles per hour, v is the speed of the sound source, in this case the car, in miles per hour f0 is the frequency of the sound when stationary Using a spectrum analyzer, we could determine the observed frequency when the car was driving away was 236 Hz and the stationary frequency was 253 Hz. Use this information and the equation to estimate the speed of the car in miles/hour, to 1 decimal place.

54.88 mph

Step-by-step explanation: the Doppler effect formulae is given below as

f' = (v + vo) /(v - vs) × f

Where f' = observed frequency = 236 Hz,

f = frequency of sound source (stationary frequency) = 253 Hz.

v = speed of sound in air = 761 mph

Since the car (source) is moving away relative to the observer, vs will have a negative value (-vs)

vo = 0 mph ( since the observer is not moving)

By substituting the parameters, we have that

236 = (761+0)/(761 - (-vs)) × 253

236 = (761/ 761 +vs) × 253

By cross multiplication, we have that

236 × (761 +vs) = 761 ×253

761 + vs = 761 ×253/ 236

761 + vs = 192533/ 236

761 + vs = 815.88

vs = 815.88 - 761

vs = 54.88 mph

this story was prepared by jim

mccullaugh in los angeles and

al stewart in new york.

new york the colossal success of "top gun" appears to have dramatically altered madison avenue's

perception of corporate sponsorship

of home video projects.

the paramount home video re- lease, featuring a 60- second diet

pepsi spot, was by no means the

first prerecorded video to carry an advertiser's plug, but it was the

first major theatrical release to do so. in the aftermath of the title's

success, paramount is widely ex- pected to ink a similar deal for

"crocodile dundee" or "star trek

iv" or both.

corporate america's new attraccds push british

recording sales

to 19% gain

london fueled by the compact

disk boom, the value of u.k. manu- facturer shipments of recordings

rose 19% in the 12 -month period ended march 1987, according to the

british phonographic industry.

total value of u.k. shipments for

the period was $755 million for all

configurations. (all value figures

are based on an exchange rate of

$1.68 to the pound sterling.)

cd sales totaled 10.7 million units

worth $121.3 million- compared

with 3.7 million units worth $39.5

million in the prior 12 months -and

accounted for two -thirds of the

overall gain in trade value. at present growth rates, says the bpi, cd

sales for calendar 1987 will reach 20

(continued on page 79)

step-by-step explanation: