A car moving with a velocity of 36 km/hr crosses a siren of frequency 500 Hz.

A car moving with a velocity of 36 km/hr crosses a siren of frequency 500 Hz. The apparent frequency of siren after passing it will be

Options

(a) 520 Hz
(b) 485 Hz
(c) 540 Hz
(d) 460 Hz

Correct Answer:

485 Hz

Explanation:

Velocity of the car = 36000 m / 3600 s = 10 m/s
ʋemitted = 500 Hz, ʋsound = 330 m/s
ʋobs = ʋemitted [(ʋsound – ʋobs) / ʋsound]
Observed frequency ʋobs = 500 [(300 – 10) / 300]
⇒ ʋobs = 485 Hz

admin:

Related Questions

  1. The earth is assumed to be a sphere of radius R. A platform is arranged at a height R
  2. Two charges placed in air repel each other by a force of 10⁻⁴ N. When oil is
  3. A conveyor belt is moving at a constant speed of 2 m/s. A box is gently dropped on it
  4. A closely wound solenoid of 2000 turns and area of cross-section 1.5 x 10⁻⁴ m² carries
  5. If alpha, beta and gamma rays carry same momentum, which has the longest