You double your distance from a sound source that is radiating equally in all di

Question

You double your distance from a sound source that is radiating equally in all directions. What happens to the intensity of the sound? It reduces to one-fourth its original value. One-eighth its original value. One-sixteenth its original value. None of the above A copper wire of length 2.0 m, cross sectional area 7.1 times 10^6 m2 and Young's modulus 11 times 10^10 N/m^2 has a 200-kg load hung on it. What is its increase in length? (g = 9.8 m/s^2) 0.50 mm 1.0 mm 2.5 mm 5.0 mm The coefficient of linear expansion of steel is 12 times 10^-6 K^-1. What is the change in length of a 25-m steel bridge span when it undergoes a temperature change of 40 K from winter to summer? 1.2 cm 1.4 cm 1.6 cm 1.8 cm 2.0 cm

Explanation / Answer

6)
I = P/A
As we double the distance, Anew = 4**(2r)^2 = 4* (4**r^2)

Inew = 1/4 * P/A
Inew = 1/4 * I
Correct option :- (A) One forth it's original value !!

7)
young's modulus, E = Stress/Strain
Where,
Stress = F/A
Strain = L/L

Substituing Values,
11 * 10^10 = [(200*9.8)/(7.1*10^6)] / [L/2.0]
L = 5.0 mm

8)
= 12.0 * 10^-6 k^-1
L = 25 m
T = 40 K

L = L**T
L = 25 * 12.0 * 10^-6 * 40 m
L = 0.012 m
L = 1.2 cm

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