Quantrex Quantrex AcademyJEE · NEET · NDA PYQs with solutions Open app
JEE Main2015PhysicsWaves and SoundActual

A source of sound emits sound waves at frequency f 0 . It is moving towards an observer with fixed speed v s ( v s < v) , where v is the speed of sound in air). If the observer were to move towards the source with speed v 0 , one of the following two graphs (A and B) will give the correct variation of the frequency f heard by the observer as v 0 is changed. The variation of f with v 0 is given correctly by:

Options

  1. AGraph A with slope = f 0 v - v s
  2. BGraph A with slope = f 0 v + v s
  3. CGraph B with slope = f 0 v - v s
  4. DGraph B with slope = f 0 v + v s

Correct answer

A. Graph A with slope = f 0 v - v s

Step-by-step solution

f a p p = v + v 0 v - v s f 0 ⇒ f = f 0 v - v s v 0 + v f 0 v - v s On comparing with y = m x + c m = f 0 v - v s and c = v f 0 v - v s ⇒ Graph with +ve slope and +ve intercept.

Practice Waves and Sound on Quantrex Academy →

More from Waves and Sound

List-I shows four configurations made of straight and semi-circular narrow tubes containing air. A sound wave of wavelength = 0.29 m enters these structures at the point S and a so 2026A transverse wave on a string is described by y = 3 (36t + 0.018x + /4) , where x, y are in cm and t in seconds. The least distance between the two successive crests in the wave is 2026The equation of a plane progressive wave is given by y = 5 (200t - x 150 ) where x and y are in cm and t is in second. The velocity of the wave is _______ m/s. 2026The speed of a longitudinal wave in a metallic bar is 400 ~m / s . If the density and Young's modulus of the bar material are increased by 0.5 % and 1 % , respectively then the spe 2026Two tuning forks A and B are sounded together giving rise to 8 beats in 2 s. When fork A is loaded with wax, the beat frequency is reduced to 4 beats in 2 s. If the original freque 2026A point source is kept at the center of a spherically enclosed detector. If the volume of the detector increased by 8 times, the intensity will 2026The fifth harmonic of a closed organ pipe is found to be in unison with the first harmonic of an open pipe. The ratio of lengths of closed pipe to that of the open pipe is 5 / x . 2026The velocity of sound in air is doubled when the temperature is raised from 0^ C to ^ C . The value of is _ _ _ _ . 2026 Full Waves and Sound list All JEE Main PYQs