A Wave Pulse Starts Propagating In +x-direction Along A Non-uniform Wire Of Length 10 M With Mass Per Unit Length Given m = m0 + αx and Under A Tension Of 100 N. Find The Time Taken By The Pulse To Travel From The Lighter End (x = 0) To The Heavier End. (m0 = 10–2 kg/m and α = 9 × 10–3 kg/m2)

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A wave pulse starts propagating in +x-direction along a non-uniform wire of length 10 m with mass per unit length given m = m0 + αx and under a tension of 100 N. Find the time taken by the pulse to travel from the lighter end (x = 0) to the heavier end. (m0 = 10–2 kg/m and α = 9 × 10–3 kg/m2)


Correct option is

2.335 sec


Velocity of transverse wave in a string,


Integrating within proper limits,







             = 2.335 sec.



Determine the change in volume of 6 litres of alcohol if the pressure is decreased from 200 cm of Hg to 75 cm. [Velocity of sound in alcohol is 1280 m/s, density of alcohol = 0.81 g/cc, density of Hg = 13.6 g/cc and g = 9.81 m/s2]



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(b) Calculate the ratio of the speed of sound in neon to that in water vapours at any temperature. [Molecular weight of neon = 2.02 × 10–2kg/mol and for water vapours = 1.8 × 10–2 kg/mol]


(a) Find the speed of sound in a mixture of 1 mol of helium and 2 mol of oxygen at 27oC. (b) If the temperature is raised by 1 K to 300 K, find the percentage change in the speed of sound in the gaseous mixture. (R = 8.31 J/mol K). 


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What is the maximum possible sound level in dB of sound waves in air? Given that density of air = 1.3 kg/m3v = 332 m/s and atmospheric pressure  



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(b) How much more intense is an 80 dB sound than a 20 dB whisper?


A window whose area is 2 m2 opens on a street where the street noise result in an intensity level at the window of 60 dB. How much ‘acoustic power’ enters the window via sound waves. Now if an acoustic absorber is fitted at the window, how much energy from street will it collect in five hours? 


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An observer is at a distance of one metre from a point light source whose power output is 1 kW. Calculate the magnitude of electric and magnetic fields assuming that the source is monochromatic, it radiates uniformly in all directions and that at the point of observation it behaves like a travelling plane wave. Given that H/m and 


Decibel is: