What is the intensity of sound 2?

AI Thread Summary
Sound 2's intensity level is 2.5 dB higher than Sound 1, which has an intensity of 39.0 W/m². The relationship between intensity levels can be expressed using the formula 2.5 dB = 10 log(I2/I1). By rearranging this equation and substituting I1, the correct intensity for Sound 2 can be calculated. The initial calculations presented were incorrect, leading to confusion. The problem can be simplified by directly applying the logarithmic relationship to find I2.
eagles12
Messages
76
Reaction score
0

Homework Statement



Sound 1 has an intensity of 39.0 W/m^2. Sound 2 has an intensity level that is 2.5 dB greater than the intensity level of sound 1. What is the intensity of sound 2?

Homework Equations



I=energy/area*time
β=(10dB) logI/Io
Io=10^-12 W/m^2

The Attempt at a Solution



Intenisty 1= 39=energy/area*time
β for the second sound= 339.776
Using this i plugged in
339.776=(10dB) logI/Io
33.977=logI/Io
9.49*10^33=I/Io
and found I=9.5*10^21 but it is saying this is incorrect
 
Physics news on Phys.org
eagles12 said:

Homework Statement



Sound 1 has an intensity of 39.0 W/m^2. Sound 2 has an intensity level that is 2.5 dB greater than the intensity level of sound 1. What is the intensity of sound 2?

Homework Equations



I=energy/area*time
β=(10dB) logI/Io
Io=10^-12 W/m^2

The Attempt at a Solution



Intenisty 1= 39=energy/area*time
β for the second sound= 339.776
Using this i plugged in
339.776=(10dB) logI/Io
33.977=logI/Io
9.49*10^33=I/Io
and found I=9.5*10^21 but it is saying this is incorrect
I'm not following your logic on that. :rolleyes:

I think you might be making this problem harder than it is. When the problem statement says, "Sound 2 has an intensity level that is 2.5 dB greater than the intensity level of sound 1" that means,

2.5 \ \mathrm{dB} = 10 \ \log \frac{I_2}{I_1}
where I1 is given as 39.0 W/m2. Solve for I2. :wink:
 
I multiplied the values first without the error limit. Got 19.38. rounded it off to 2 significant figures since the given data has 2 significant figures. So = 19. For error I used the above formula. It comes out about 1.48. Now my question is. Should I write the answer as 19±1.5 (rounding 1.48 to 2 significant figures) OR should I write it as 19±1. So in short, should the error have same number of significant figures as the mean value or should it have the same number of decimal places as...
Thread 'A cylinder connected to a hanging mass'
Let's declare that for the cylinder, mass = M = 10 kg Radius = R = 4 m For the wall and the floor, Friction coeff = ##\mu## = 0.5 For the hanging mass, mass = m = 11 kg First, we divide the force according to their respective plane (x and y thing, correct me if I'm wrong) and according to which, cylinder or the hanging mass, they're working on. Force on the hanging mass $$mg - T = ma$$ Force(Cylinder) on y $$N_f + f_w - Mg = 0$$ Force(Cylinder) on x $$T + f_f - N_w = Ma$$ There's also...
Back
Top