Solution:

For a travelling wave, `y = A sin(omegat - Kx),` be the displacement. The velocity of particles is

given by `v+p = (dy/dt) = omegaA cos(omegat -Kx)`

K.E. per unit volume

`1/2 m/v v^2 = 1/2 pv^2`



:. K.E. density defined as K.E. per unit

volume is given by `1/2 pomega^2 A^2 cos^2 (omegat-Kx)`

Maximum value of energy density

`= 1/2 pomega^2A^2`

Intensity is the energy falling per unit area per unit time.


So, `I = (DeltaE)/(DeltatS) = P/S`

`I = (1/2pomega^2 A^2 . SDeltax)/(SDeltat) =1/2 pomega^2A^2v`

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Solution:

The temperature coefficient of the velocity of sound is defined as the change in the velocity of sound, when the temperature changes by `1°C` (or 1 K). It is denoted by `alpha`.

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Solution:

Given wave : `Y_i =A sin(omegat- Kx)`

Reflected wave :
`Y_r = A sin(omegat +Kx +pi)`

`= - A sin(omegat+Kx)`

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Solution:

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Solution:

Standing waves are the pattern of waves produced when two waves moving in opposite direction interact. They do not transport energy.

If a wave 'A' is made to hit a rigid support, there will be a reflected wave 'B' from the rigid support. As the two waves are super imposed, there will be a standing wave (as shown) produced. It can be represented by the equation, `y = 2A sin kx` cos wt indicating a position varying amplitude `(2A sin kx)`

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Solution:

Let S and 0 be the source and observer. If v is the frequency of sound with velocity v released by the source, then number of waves will be received by the observer at rest. When the source approaches the stationary observer, the number of waves received increases due to the apparent shortening of the wavelength. Wavelength perceived

`lambda= (velocity of sound w.r.t. moving source)/(frequency)`

`: . lambda = (u-u_s)/v`

using `lambda= l/v` we get

and `u/v = (v-v_s)/v ; v' = v (v/(v-v_s))`

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Solution:

Let u be the velocity of sound and `u_8` be the velocity of source towards observer. As the source approaches, the space between source and observer gets reduced but should accomodate the same number of waves (as frequency). So, wavelength reduces. The new waveiength is,

`lambda' = text(velocity of sound w.r.t. source)/text(frequency)`

`= (v-v_s)/v`

Also `lambda = u/v`

`v' =v (v/v-v_s)`

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Solution:

Whenever there is a relative motion between a source of sound and listener, the apparent frequency of sound heard by listener is different from actual frequency of sound emitted by the source. Let S be a source of sound and L, the listener of sound, both initially at rest. Let u be the actual frequency of sound emitted by the source and A be the actual wavelength of sound emitted. If u is velocity of sound in still air, then `lambda= u/v`

Let the distance between source and listener be V, so that v waves from the source reach listener in 1 second. `V, =` Velocity of medium,

`V_s =` Velocity of source, `V_L =` Velocity of listener

Resultant velocity of sound along
`SL = (V + V_m)`
SS' = distance proved by source in 1 sec.
`= V_s along SL`
. . Relative velecity of sound w.r.t. source
`= f(V +V_m)- V_sl`
As the frequency remains unchanged.

V waves emitted in one second occupy
the distance `[(V + V_m) - V_sl`

`lambda = [(V+V_m -V_s]`

`LL' = VL` Relative vel. of sound waves w.r.t listener `(V + Vm) - VL`
Apparent frequency of sound waves heard by listener is


`v' ((V+B_m)- V_L)/lambda`


`v' ( [(V+B_m)- V_L)/(V+ V_m )-V_S]) =V`

when both approach each other

`V_S = (+), V_L = (-)`

`V' = (V- (-V_L))/(V-V_S) V = (V+V_L)/(V-V_S) )V`

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Solution:

Let u be the velocity of sound and `u_8` be the velocity of source towards observer. As the source approaches, the space between source and observer gets reduced but should accomodate the same number of waves (as frequency). So, wavelength reduces. The new waveiength is,

`lambda' = text(velocity of sound w.r.t. source)/text(frequency)`

`= (v-v_s)/v`

Also `lambda = u/v`

`v' =v (v/v-v_s)`

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