Physics I / Sound Waves and the Doppler Effect
Practice question · Estimate

A source emits sound at 500Hz500 Hz and moves toward a stationary observer at 34m/s34 m/s. Taking the speed of sound as 340m/s340 m/s, the observed frequency is approximately ___ Hz. Set the slider to your answer.

Estimate on a scale from 0 to 2000.

Hints
  1. An approaching source crowds the wavefronts, so the pitch rises.
  2. The source speed is subtracted in the denominator, not added.
Show the answer

555.6 (answers within ±20 count)

Why

fobs=f×v/(vvs)=500×340/(34034)=500×340/306555.6f_{obs} = f \times v/(v - v_s) = 500 \times 340/(340 - 34) = 500 \times 340/306 \approx 555.6 Hz.

Read the lesson: Sound Waves and the Doppler Effect →

Practise Sound Waves and the Doppler Effect

The app has 6 more questions on this lesson, and keeps your place in the course. Physics I is free to start.

More questions on Sound Waves and the Doppler Effect