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NTA Abhyas JEE Main2020PhysicsWaves and SoundPractice

An open pipe of sufficient length is dipping in water with a speed v vertically. If at any instant l is the length of the tube above water. Then the rate at which fundamental frequency of pipe changes, is (speed of sound = c )

Options

  1. Ac v 2 l 2
  2. Bc v 4 l 2
  3. Cc 2 v 2 l 2
  4. Dc 4 v 2 l 2

Correct answer

B. c v 4 l 2

Step-by-step solution

f = c 4 l ∴            df dt = c 4 l 2 d l dt = cv 4 l 2

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