F = focal lenght = 67.1 cm
u= distance between mirror and object = 16.76 cm
1/f = 1/v + 1/u
1/67.1 = -1/16.76 + 1/u
1/67.1 + 1/16.76 = 1/u
u = 13.41
Answer:
The second distance of the sound from the source is 431.78 m..
Explanation:
Given;
first distance of the sound from the source, r₁ = 1.48 m
first sound intensity level, I₁ = 120 dB
second sound intensity level, I₂ = 70.7 dB
second distance of the sound from the source, r₂ = ?
The intensity of sound in W/m² is given as;
![dB = 10 Log[\frac{I}{I_o} ]\\\\For \ 120 dB\\\\120 = 10Log[\frac{I}{1*10^{-12}}]\\\\12 = Log[\frac{I}{1*10^{-12}}]\\\\10^{12} = \frac{I}{1*10^{-12}}\\\\I = 10^{12} \ \times \ 10^{-12}\\\\I = 1 \ W/m^2](https://tex.z-dn.net/?f=dB%20%3D%2010%20Log%5B%5Cfrac%7BI%7D%7BI_o%7D%20%5D%5C%5C%5C%5CFor%20%5C%20120%20dB%5C%5C%5C%5C120%20%3D%2010Log%5B%5Cfrac%7BI%7D%7B1%2A10%5E%7B-12%7D%7D%5D%5C%5C%5C%5C12%20%3D%20%20Log%5B%5Cfrac%7BI%7D%7B1%2A10%5E%7B-12%7D%7D%5D%5C%5C%5C%5C10%5E%7B12%7D%20%3D%20%5Cfrac%7BI%7D%7B1%2A10%5E%7B-12%7D%7D%5C%5C%5C%5CI%20%3D%2010%5E%7B12%7D%20%5C%20%5Ctimes%20%5C%2010%5E%7B-12%7D%5C%5C%5C%5CI%20%3D%201%20%5C%20W%2Fm%5E2)
![For \ 70.7 dB\\\\70.7 = 10Log[\frac{I}{1*10^{-12}}]\\\\7.07 = Log[\frac{I}{1*10^{-12}}]\\\\10^{7.07} = \frac{I}{1*10^{-12}}\\\\I = 10^{7.07} \ \times \ 10^{-12}\\\\I = 1 \times \ 10^{-4.93} \ W/m^2](https://tex.z-dn.net/?f=For%20%5C%2070.7%20dB%5C%5C%5C%5C70.7%20%3D%2010Log%5B%5Cfrac%7BI%7D%7B1%2A10%5E%7B-12%7D%7D%5D%5C%5C%5C%5C7.07%20%3D%20%20Log%5B%5Cfrac%7BI%7D%7B1%2A10%5E%7B-12%7D%7D%5D%5C%5C%5C%5C10%5E%7B7.07%7D%20%3D%20%5Cfrac%7BI%7D%7B1%2A10%5E%7B-12%7D%7D%5C%5C%5C%5CI%20%3D%2010%5E%7B7.07%7D%20%5C%20%5Ctimes%20%5C%2010%5E%7B-12%7D%5C%5C%5C%5CI%20%3D%201%20%5Ctimes%20%5C%2010%5E%7B-4.93%7D%20%5C%20W%2Fm%5E2)
The second distance, r₂, can be determined from sound intensity formula given as;
Therefore, the second distance of the sound from the source is 431.78 m.
Answer:
<u><em>1) if they are moving away from each other it will take 1.43 secs</em></u>
<u><em>2) if they are moving towards each other then it will take 1.11 secs</em></u>
Explanation:
Distance between them is 10 m
Speed ( if they are moving towards each other)= distance/time
time = 10/8+1
time = distance / speed= 10/9= 1.11 secs
if they are moving away from each other than it will take
time = 10/8-1= 10/7= 1.43 secs
Geology is the study of the Earth, the materials of which it is made, the structure of those materials, and the processes acting upon them.
