# UNIT-2:Application of Sound Waves¶

## Example no:2.1,Page no:41¶

In [11]:
#Variable declaration
v=3000              #volume in metre cube.
theta=0.2           #theta in owu(open window unit).
s=1850              #area in metre cube.

#Calculation
a=theta*s     #calculating total absorbtion of surface.
T=(0.165*v)/a #calculating T using Sabine formula

#Result
print"Reverberation time of Room = ",round(T,2) ,"sec"

Reverberation time of Room =  1.34 sec


## Example no:2.2,Page no:41¶

In [39]:
#Variable declaration
v=120000                            #volume in metre cube.
t=1.5                               #time in second.
s=25000                             #area in metre cube.

#Calculation
a=(0.16*v)/(t*s)                   #using Sabine formula for calculating a

#Variable declaration
print"Average Absorbing Power of Surface = ",a,"o w u"

Average Absorbing Power of Surface =  0.512 o w u


## Example no:2.3,Page no:42¶

In [37]:
#Variable declaration
v=6000.0                    #Volume in metre cube.
a=20.0                     #surface absorbtion in owu(open window unit).

#Calculation
T=(0.165*v)/(a)            #calculating T using Sabine Formula.

#Result
print"Reverberation Time = ",T,"sec"
print"\nNOTE:Calculation mistake in book"

Reverberation Time =  49.5 sec

NOTE:Calculation mistake in book


## Example no:2.4,Page no:42¶

In [40]:
v=3500                  #volume in metre cube.
n1=370-300              #no. of audience on wooden seats.
n2=300-70               #no. of empty wooden seats.

#Calculation
a1s1=0.04*60            #absorption due to wooden doors.
a2s2=0.03*700           #absorption due to plastered walls.
a3s3=0.06*50            #absorption due to glass work.
a4s4=4.2*370            #absorption due to audience on spungy and wooden
#seats.
a5s5=2*230               #absorption due to empty seats.
sum=a1s1+a2s2+a3s3+a4s4+a5s5  #total absorption of cinema hall.
T=(0.165*v)/sum          #calculating T using Sabine Formula.

#Result
print"Reverberation Time = ",round(T,2),"sec"

Reverberation Time =  0.28 sec


## Example no:2.5,Page no:49¶

In [28]:
import math

#Variable declaration
l=10                           #length in centimetres.
Y=20*10**11                     #Young's Modulus in dyne/cm square.
R=8                            #Density in gram/cc

#Calculation
n=(1.0/(2*l))*math.sqrt(Y/R)  #calculating frequency of vibration using
#young's modulus.

#Result
print"Frequency of vibration=",n,"Hz"

Frequency of vibration= 25000.0 Hz


## Example no:2.6,Page no:50¶

In [26]:
import math

#Variable declaration
t=0.1                #thickness in centimetre.
Y=8.75*10**11         #Young's Modulus in dyne/cm square.
R=2.654              #Density in gram/cm square.

#Calculation
n=(1/(2*t))*math.sqrt(Y/R)      #calculating frequency using Young's modulus.

#Result
print"Frequency of Vibration=",round(n),"Hz"

Frequency of Vibration= 2870936.0 Hz


## Example no:2.7,Page no:50¶

In [18]:
#Variable declaration
K=2.026*10**9               #Bulk Modulus in N/m square.
R=10**3                     #Density in Kg/m cube.

#Calculation
V=math.sqrt(K/R)                #Calculating speed using Bulk Modulus.

#Result
print"Velocity of sound waves in water = ",round(V,2),"m/sec"

Velocity of sound waves in water =  1423.38 m/sec


## Example no:2.8,Page no:51¶

In [16]:
import math

#Variable declaration
Y=1.41             #Young's Modulus.
R=1.293*10**-3      #Density of air in g/centimetre cube.
P=76*13.6*980      #atmospheric pressure in dyne/cm square.

#Calculation
V=math.sqrt((Y*P)/R)     #calculating speed using young's modulus.

#Result
print"Speed of ultrasonic wave in air at n.t.p=",round(V*10**-2,1),"m/sec"

Speed of ultrasonic wave in air at n.t.p= 332.4 m/sec