A car moving at 30 m/s toward an observer sounds its horn at 400 Hz. If the speed of sound is 343 m/s, what frequency does the observer hear?
Correct answer: C. 436 Hz
- A. 368 Hz
- B. 400 Hz
- C. 436 Hz
- D. 472 Hz
Explanation
Explanation: Doppler effect: f' = f × (v / (v - vs )) = 400 × (343 / (343 - 30)) = 400 × (343 / 313) ≈ 436 Hz.
Report an error
The more specific you are, the faster it gets fixed. A source beats an opinion.
Prefer email? [email protected]
About Waves
Progressive waves transfer energy through oscillations, with wavelength, frequency, amplitude and wave speed related by v = fλ; sound speed depends on the medium. Superposition produces interference and stationary waves in strings and organ pipes, while simple harmonic motion describes the oscillation itself and must be distinguished from wave propagation.
Practise Waves
1,281 free Waves MCQs from Physics, each with the correct answer and an explanation. Unlimited attempts, no account needed.
Discussion
Stuck on an option, or know a faster way to get there? Ask or explain it here.
No comments yet. Be the first to explain this one.
Exams that ask Physics questions like this
Physics is on 16 papers prepared for on TestUstad, and all of them draw the same bank, so this question is worth knowing for every one of them.
More Waves questions
Two waves with frequencies 500 Hz and 510 Hz produce beats. What is the beat frequency?
An open pipe of length 0.85 m resonates at its fundamental frequency. What is this frequency? (Speed of sound = 343 m/s)
A sound source produces 10⁻⁴ W/m² at a distance of 2 m. What is the intensity at 4 m?
A standing wave in a closed pipe (one end closed) has a length of 0.5 m. What is the wavelength of the second harmonic? (Speed of sound = 343 m/s)
Bats navigate and find food by:
Which one of the following explains that all the galaxies are receding from us?