PHYSICS-URGENT HELP

A stationary police car emits a sound of frequency 1200 Hz that bounces off of a car on the highway and returns to the police car with a frequency of 1250 Hz. The police car is right next to the highway, so the moving car is traveling either directly towards or directly away from the parked officer. Determine the car’s velocity, and whether the car was traveling towards or away from the police car.

  1. 👍 0
  2. 👎 0
  3. 👁 400
asked by Brit
  1. F = ((V + Vr) / (V + Vs)) * Fo = 1250.
    ((343 + Vr) / (343 + 0)) * 1200 = 1250,
    Divide both sides by 1200:
    (343 + Vr) / 343 = 1.0417,
    Multiply both sides by 343:
    343 + Vr = 357.29,
    Vr = 357.29 - 343 = 14.3m/s Toward the
    police car.

    Vr = Velocity of the receiver(car).
    Vs = Velocity of the source(police car.

    1. 👍 0
    2. 👎 0
    posted by Henry
  2. The answer said it was 7.02 m/s and not 14.3 m/s

    1. 👍 0
    2. 👎 0
    posted by Brit

Respond to this Question

First Name

Your Response

Similar Questions

  1. physics

    A police car siren emits a sound wave with a frequency fs = 400 Hz and it is moving toward the wall at 25 /m/s. What frequency reflected from the wall does the driver of the police car hear ? The speed of sound is 340 m/s.

    asked by Thomas on January 11, 2016
  2. physics

    A speeding car is pulling away from a police car. The police car is moving at 30 m/s. The radar gun in the police car emits an electromagnetic wave with a frequency of 20.0 x 10^9 Hz. The wave reflects from the speeding car and

    asked by Liz on August 21, 2010
  3. physics 2

    A siren on the top of the police car moving with a speed of 40 m/s emits sound at frequency of 820Hz. Ahead of the car, there is a truck moving in the same direction as the car but with a speed of 30 m/s. Assume the speed of sound

    asked by Maria on April 28, 2018
  4. Physics

    A stationary observer hears a sound with a frequency of 450 Hz from an approaching car. If the car emits the sound at a frequency of 360 Hz, what would be the speed of the car? (Speed of sound 340 m/s)

    asked by Bob on February 6, 2015
  5. physics

    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

    asked by Jon on April 6, 2008
  6. physics

    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

    asked by Jon on April 6, 2008
  7. physics

    a car, moving at 100 mi/hr, passes a stationary police car whose siren has a frequency of 500 Hz. what is the frequency change heard by observer in the moving car as he passes the police car? the velocity of sound in air is 343

    asked by OMAR on May 30, 2011
  8. PHY1015S

    A policeman in a stationary car measures the speed of approaching cars by means of an ultrasonic device that emits a sound with a frequency of 41.2 kHz. A car is approaching him at a speed of 33.0 m/s. The wave is reflected by the

    asked by Bhodloza on October 7, 2014
  9. Physics

    A motorcycle and a police car are moving toward one another. The police car emits sound with a frequency of 512 Hz and has a speed of 28.0 m/s. The motorcycle has a speed of 13.0 m/s. What frequency does the motorcyclist hear?

    asked by Cooper on November 22, 2011
  10. Physics

    A stationary whistle emits a sound of 188 Hz. If passengers in a car hear the whistle with a frequency of 198 Hz, how fast was the car moving? Use 340 m/s for the sound velocity

    asked by Sav on January 9, 2013

More Similar Questions