Quantrex Quantrex AcademyJEE · NEET · NDA PYQs with solutions Open app
BITSAT 2020
Exam
BITSAT
Year
2020
Subject
Physics
Chapter
Waves and Sound

BITSAT 2020 · Physics · Waves and Sound

A whistle of frequency 1000 Hz is sounded on a car travelling...

A whistle of frequency 1000Hz1000 \mathrm{ Hz} is sounded on a car travelling towards a cliff with velocity of 18 ms−1\mathrm{ m} \mathrm{ s}^{-1} normal to the cliff. If c=330ms−1\mathrm{c}=330 \mathrm{ m} \mathrm{ s}^{-1}, then the apparent frequency of the echo as heard by the car driver is nearly

Options

  1. A1115Hz1115 \mathrm{ Hz}
  2. B115Hz115 \mathrm{ Hz}
  3. C67Hz67 \mathrm{ Hz}
  4. D47.2Hz47.2 \mathrm{ Hz}

Correct answer

A. 1115Hz1115 \mathrm{ Hz}

Step-by-step solution

By the concept of accoustic, the observer and source are moving towards each other, each with a velocity of 18ms−1∴\mathrmv′=330+18330−18×1000≈1115Hz18 \mathrm{ m} \mathrm{ s}^{-1}\therefore \mathrmv^{\prime}=\frac{330+18}{330-18} \times 1000 \approx 1115 \mathrm{ Hz}
Practice Waves and Sound on Quantrex Academy →

More from Waves and Sound

The speed of sound in oxygen at S.T.P. will be approximately: (Given, .R=8.3 JK^ -1… BITSAT 2024A plane progressive wave is given by y=2 2 π(330 t-x) m . The frequency of the wave is: BITSAT 2024The engine of a train moving with speed 10 ms^ -1 towards a platform sounds a whistle at… BITSAT 2023The ratio of speed of sound in hydrogen gas to the speed of sound in oxygen gas at the… BITSAT 2023A submarine A travelling at 17 m / s is being chased along the line of its velocity by… BITSAT 2022Transverse waves of the same frequency are generated in two steel wires A and B . The… BITSAT 2022A direct current of 6 A is superimposed on an alternating current I=10 ω t flowing… BITSAT 2022The frequency of whistle of an engine appears to be (4 / 5)^ th of initial frequency when… BITSAT 2021 Full Waves and Sound list All BITSAT PYQs