Abystander hears a siren vary in frequency from 588 hz to 398 hz as a fire truck approaches, passes by, and moves away on a straight street. what is the speed of the truck?

v_s = 66.09 m/s

Explanation:

given,

Varying frequency of the siren = 588 Hz to 398 Hz

speed of sound = 343 m/s

speed of truck calculation

using equation of Doppler's

When the truck is approaching

......(1)

Doppler's equation when truck is moving away

...........(2)

equating both the equation

on simplifying the above equation we get

f_0 = 588 Hz

f_1 = 398

now,

    v_s = 66.09 m/s

speed of the truck is equal to v_s = 66.09 m/s